• <tr id="yyy80"></tr>
  • <sup id="yyy80"></sup>
  • <tfoot id="yyy80"><noscript id="yyy80"></noscript></tfoot>
  • 99热精品在线国产_美女午夜性视频免费_国产精品国产高清国产av_av欧美777_自拍偷自拍亚洲精品老妇_亚洲熟女精品中文字幕_www日本黄色视频网_国产精品野战在线观看 ?

    Ru thickness-dependent interlayer coupling and ultrahigh FMR frequency in FeCoB/Ru/FeCoB sandwich trilayers

    2022-08-31 09:55:28LeWang王樂(lè)ZhaoXuanJing荊照軒AoRanZhou周傲然andShanDongLi李山東
    Chinese Physics B 2022年8期
    關(guān)鍵詞:山東

    Le Wang(王樂(lè)) Zhao-Xuan Jing(荊照軒) Ao-Ran Zhou(周傲然) and Shan-Dong Li(李山東)

    1College of Physics,Qingdao University,Qingdao 266071,China

    2College of Electronics and Information,Qingdao University,Qingdao 266071,China

    Keywords: interlayer exchange coupling,optical mode resonance,acoustic mode resonance,component gradient sputtering

    1. Introduction

    In 1988, Heinrichet al. observed optical mode ferromagnetic resonance (FMR) caused by interlayer exchange coupling (IEC) in an ultrathin epitaxial single crystal Ni/Fe bilayer.[1]The IEC was widely used in magnetic devices,[2,3]such as magnetic recording devices, giant magnetoresistance effect, tunneling magnetoresistance effect,[4–8]etc. The materials currently used to study IEC are mainly composed of Fe,[9–11]Co,[12]FeCo,[13]NiFe,[14–17]and FeCo alloys,[18–34]separated by non-ferromagnetic materials, such as Cu,[14,35]Cr,[9,36]and Ru.[3,15–18,24–26,37]For the FM/NM/FM structure,the coupling strength and type of IEC are mainly related to the material compositions and the thickness value of FM layer and NM layer. However,the mechanism of IEC has not been completely understood so far, which still requires further studying. Very recently,an ultrahigh OM FMR was observed in the AFM coupled FM/NM/FM sandwich trilayers, where the antiferromagnetic IEC field,as a driving force,is responsible for the ultrahigh OM FMR frequency. Therefore, controlling the coupling type to obtain a strong AFM coupling is particularly important.Theoretically,McKinnonet al.[8]and Neel[38]systematically investigated the effect of the exchange coupling coefficientsJ1andJ2on the FMR frequency and intensity of thin films. In this study,FeCoB/Ru/FeCoB trilayers were prepared by a compositional gradient sputtering method. It was revealed that an ultrahigh FMR frequency over 20 GHz and an oscillation of IEC with Ru thickness were observed. The experimental results were simulated by the Layadi’s rigid model.The experimental and theoretical results were well consistent with each other.

    Usually, two resonance modes, the acoustic mode (AM,the two FM layers precessing in-phase)and the optical mode(OM)(the two FM layers precessing out-of-phase),appear in the FM/NM/FM systems whether the coupling type is FM or AFM.[36]However,the definitions of resonance modes are often inconsistent for different FM material systems. For an FM coupling system, the determination of the resonance mode is relatively simple. The frequency of the OM is higher than that of the AM.But the frequency dispersion is very complex for an AFM coupling system. It is not suitable to determine AM or OM simply from the relative frequency. Therefore,it is very important to judge the mode of resonance peak by other means. With the development of modern testing technology,we found that by combining transverse(T)and longitudinal (L) ferromagnetic resonance (FMR) tests, the modes of resonance peaks can be identified intuitively and effectively. It is also a useful method to evaluate the exchange coupling strengths for both FM and AFM coupled systems.[37]In the conventional transverse pumping FMR (T-mode), the microwave field ?his applied perpendicular to the external bias field (H) direction, which results in a strong coupling in the AM and a weak coupling in the OM [Fig. 1(b)]. The dynamic magnetization components parallel to ?hfrom both FM layers are added to each other in the case of in-phase precession in the transverse configuration. This leads to a strong absorption of the AM resonance. While for the OM,the dynamic magnetizations parallel to ?hcancel out due to the out-of-phase precession.[8]If the two ferromagnetic layers are exactly identical, the OM is perfectly canceled in the FMR spectra.[37]In comparison,the longitudinal pumping(Lmode)FMR,as reported by Zhang in 1994,is very sensitive to the OM resonance.[39]With longitudinal pumping, ?his along the external bias field direction and can couple with the OM to produce a noticeable absorption at resonance, especially when the magnetizations of the two FM layers are antiparallel to each other, while the in-phase dynamic magnetizations are canceled out[Fig.1(c)].This leads to enlarged OM and reduced AM resonance peaks.[27–35]The resonance mode can be easily identified from the relative intensities of the resonance peaks.

    2. Experiment

    The FeCoB (25 nm)/Ru (tRu?A)/FeCoB (25 nm) trilayers (defined as TL) were prepared by a composition gradient sputtering (CGS) through using RF magnetron sputtering at room temperature with a background vacuum better than 5×10?5Pa, using a (100) single crystal Si substrate with a dimension of 65 mm in length, 5 mm in width, and 0.5 mm in thickness. Several B-chips with 5 mm×5 mm wasplaced on the Fe70Co30target along the radial direction as shown in Fig.1(a). The Si substrate was pasted on the sample turntable with its length direction along the B arrangement direction.It should be mentioned here that the turntable does not rotate during the deposition of the FeCoB film. As a result,a B composition gradient with an increasing B composition from left to right will be formed along the length(R)direction[Fig.1(a).As for the preparation process of FeCoB/Ru/FeCoB trilayers,it can be described as follows. Firstly, a 25-nm-FeCoB film was deposited using the CGS method above with power of 60 W and Ar pressure of 0.5 Pa at an Ar flow rate of 60 sccm.Secondly,a uniform Ru spacer layer was deposited on the top of the 25-nm-FeCoB layer through using the turntable speed of 5-round per minute with the sputtering power of 45 W and pressure of 0.6 Pa at an Ar flow rate of 60 sccm. The Ru thickness was calculated using deposition time according to the Ru deposition rate. Finally, another 25-nm-FeCoB layer was deposited on the Ru layer under the same CGS conditions as that on the bottom FeCoB layer. As a control,a 50-nm FeCoB single layer (defined as SL) was prepared under the same CGS conditions. The SL and TL samples were cut into 13 segments each with length of 5 mm along the length direction,and were numbered sequentially according to sample positionsn=1–13(from left to right along the length direction).

    The static magnetic properties of the samples were investigated using an alternating gradient magnetometer(AGM,MicroMagTM Model 2900). The dynamic properties were investigated by a vector network analyzer (VNA, Agilent N5224A) with a co-planar waveguide transmission line fixture. The profiles of T- and L-mode FMR are schematically shown in Figs. 1(b) and 1(c). The in-plane magnetic field and angle dependence of FMR frequency and intensity for each film were measured using VNA-FMR.The magnetic field dependence was investigated along the EA direction,and the angle dependence was studied using the start angle from the width direction of the sample (i.e., the 0?of the angleθcorresponds to the direction perpendicular to the length direction). The compositions of the samples were detected by a field-emission electron probe microanalyzer(FE-EPMA,JOEL JXA-8530F).

    Fig. 1. Schematic diagram of (a) component gradient sputtering (CGS)method,and the profiles of(b)T-and(c)L-mode FMR measurements along EA direction.

    3. Results and discussion

    Figure 2 shows the plots of composition versus sample position of the single layer for Fe, Co, and B elements. As illustrated,a linear distribution of compositions is obtained by this CGS method. The Fe/Co atomic ratio is 2.12,corresponding to an Fe:Co atomic deposition ratio of 1:1.1. In contrast,a linearly increasing B compositionCBwith an increment ratio of 0.479 is achieved. According to the theory of ferromagnetism,magnetostriction energy is expressed as

    whereλSis the saturation magnetostriction coefficient andσis the stress. Positive sign and negative sign of stress are taken for tensile stress and compressive stress, respectively,andθis the angle between stress and magnetization. Based on Eq.(1),for a film with a positiveλS,the compressive stress results in the arrangement of magnetic moments perpendicular to the compressive stress direction. If the intrinsic stress orientation is arranged along one direction, a uniaxial magnetic anisotropy will be formed. For the investigated films, a uniaxial stress along theR-direction is induced by the B-gradient along theR-direction. Owing to the FeCoB film with a positiveλSand compressive stress direction along theR-direction,the magnetic moment is preferentially arranged perpendicular toR-direction. Like previous researches,[40–42]the B-gradient induced uniaxial magnetic anisotropy (UMA) with easy axis perpendicular to theR-direction will result in a self-biased high-frequency FMR.

    Fig.2. Distributions of Fe,Co,and B elements in a single layer.

    3.1. Static magnetic properties

    Figures 3(a)–3(h) show the hysteresis loops of the Fe-CoB/Ru/FeCoB trilayers with various values of Ru thickness along the EA direction and the hard axis (HA) direction. As illustrated, the FeCoB single layer (tRu=0 ?A) has obvious uniaxial magnetic anisotropy[Fig.3(a)]. For the trilayer withtRu=1 ?A,the hysteresis loops(not shown here)are very similar to those for the single layer, which can be attributed to the discontinuous Ru spacer, where the ferromagnetic layers are still interconnected. For the samples with the Ru thickness greater than 2 ?A(2 ?A≤tRu≤8 ?A),the remanence along the HA is larger than that along EA, showing an AFM-like coupling with an obtuse angle (>90?) between the magnetic moments in the upper FM layer and the lower FM layer. The sample withtRu=8 ?A is a representative AFM coupled sample. The magnetic moments of the two FM layers are antiparallel at low fields, resulting in a small remanence along the EA. When the applied magnetic field increases to 21 Oe(1 Oe=79.5775 A·m?1), a spin flip occurs due to antiferromagnetic coupling and uniaxial magnetic anisotropy. When the Ru thickness further increases in a range of 9 ?A≤tRu≤14.5 ?A, the remanence along the EA is larger than that along the HA, implying that the moment angle is changed from obtuse angle into acute angle, and an FM coupling appears.When the Ru thickness reachestRu=16 ?A,the interlayer coupling type reverts to an AFM-like coupling again. The static magnetic properties reveal that an oscillation of the interlayer coupling type takes place in the FeCoB/Ru/FeCoB trilayers with the variation of Ru thickness.

    Fig. 3. Hysteresis loops along EA directiion and HA direction for Fe-CoB/Ru/FeCoB trilayers with various values of thickness Ru.

    3.2. Dynamic magnetic properties

    From the static magnetic properties above,it can be concluded that the interlayer coupling oscillation with the Ru thickness is present,and the Ru thickness intervals of 0–2,2–8, 9–14.5, above 16 ?A correspond to FM, AFM, FM, AFM couplings, respectively. For simplicity, we choose some representative thickness values for each interval to discuss.

    3.2.1. tttRRRuuu===111?A?A?A, FM coupling

    Fig. 4. Applied field-dependent FMR frequency (fr–H) curves along EA for 50-nm-FeCoB single layer in (a) T-mode and (b) L-mode, and FeCoB/Ru/FeCoB(tRu=1 ?A)trilayer in(c)T-mode and(d)L-mode.

    Fig.5. Angle dependent FMR frequency(fr-curve)at T-mode for tRu=1-?A trilayer in various magnetic fields.

    The in-plane distribution of FMR frequency and intensity are characterized by an in-plane angle rotation method (fr–θcurve). Figure 5 shows thefr–θcurves oftRu=1-?A trilayer measured at T-mode at various applied magnetic fields. Since the Ru spacer is discontinuous and FM coupling between the two ferromagnetic layers is present,the polar FMR spectra is very similar to that of the single layer. At zero applied field,thefr–θcurve looks like a pair of “parentheses”, indicating a good uniaxial magnetic anisotropy in the sample. With the applied magnetic field increasing from 50 Oe to 100 Oe,the intensity and frequency of the resonance along the EA increase,but the intensity of the resonance along the EA is enhanced with the increase of applied field, and an “8”-shapedfr–θcurves are observed in Figs.5(b)and 5(c). As the applied field further increases[Figs.5(d)and 5(f)],the magnetic moments will rotate following the applied field, leading to a superposition between the UMA field (HK) and external fields. As a result,an ellipticfr–θcurve is observed.

    Fig.6. The fr–H curves of FeCoB/Ru/FeCoB(tRu=5 ?A)trilayer along EA at(a)T-mode and(b)L-mode.

    Fig.7. The in-plane angle-dependent FMR frequency and intensity at T-mode for the tRu=5-?A trilayer in various magnetic fields.

    3.2.2. 222?A?A?A≤≤≤tttRRRuuu≤≤≤888?A?A?A, AFM coupling

    Thefr–Hcurve at T-mode for thetRu=5-?A trilayer(the representative sample),shown in Fig.6,reveals that there is an OM resonance peak at about 12 GHz in zero field[Fig.6(a)].The OM resonance can also be verified by the L-mode measurement, which is sensitive to the OM resonance, and only one OM peak is observed [Fig. 6(b)]. Comparing Fig. 6(a)with Fig.6(b),the resonance peak at higher frequency can be assigned to the OM resonance, indicating an AFM interlayer coupling in thetRu=5-?A trilayer. As the field increases, the OM resonance frequency increases slightly,but when the field reaches a critical field around 197 Oe[Fig.6(a)],the resonance mode suddenly switches from OM to AM,i.e., the interlayer coupling switches from AFM to FM. Further increasing the magnetic field,only AM resonance is observed infr–Hcurve.

    Figure 7 shows the in-plane angle-dependent FMR frequency and intensity for thetRu=5-?A trilayer in various magnetic fields.In zero field,only one OM resonance withθ=50?can be observed. In a field range of 50 Oe≤H ≤150 Oe,the AM resonance appears in the direction of the intensity maximum perpendicular to that of the OM resonance. Moreover,the intensity and frequency of the AM resonance increase with the applied magnetic field increasing, while the intensity of OM resonance decreases gradually till disappearing. The fact is consistent with the result in Fig.6(a),where the critical field of OM resonance disappearing is about 200 Oe. When the applied field further increases,thefr–θcurve,which is close to the fourfold symmetry, indicates that the magnetic moments in the upper and lower FM layer are both 90?, but because of the existence of UMA fieldHK, it deviates from complete symmetry.

    3.2.3. 999?A?A?A≤≤≤tttRRRuuu≤≤≤111444...555?A?A?A, FM coupling

    When the Ru thickness is in a range of 9 ?A≤tRu≤14.5 ?A,the interlayer coupling reverts from AFM to FM again. Taking thetRu=10-?A trilayer as a representative sample,thefr–Hcurve shown in Fig.8(a),reveals that there are two resonance modes observed at T-mode measurement. Comparing with the L-mode result [Fig. 8(b)], the resonance mode at higher frequency and lower frequency can be assigned as AM and OM modes, respectively. The intensity of AM resonance is far stronger than that of OM resonance, indicating that the FM interlayer coupling is dominated.

    Fig.8. fr–H curves along EA direction for tRu=10-?A trilayer at T-mode(a)and L-mode(b).

    Figure 9 shows the in-plane angle dependent FMR frequency and intensity at T-mode fortRu=10-?A trilayer in various magnetic fields.As illustrated,the two resonances overlap and only the AM resonance can be observed in the orthogonal directions[as indicated by the arrows in Fig.9(c)]. As the applied field increases,the frequency and intensity of the AM resonance increase. However, the intensity of the OM resonance (along 0?/180?and 90?/270?) remains very weak, and gradually combines together with the AM resonance with the increase of magnetic fields[see Figs.9(d)–9(f)].

    In addition,when the Ru thickness is 16 ?A,the interlayer coupling type reverts to the AFM coupling again, which will not be described here. The overall variations of FMR frequency and resonance modes with the Ru thickness for the trilayers along the EA direction are summarized in Fig. 10.As illustrated,when the Ru thickness is thinner than 2 ?A,theS21–fcurve of the trilayer is almost the same as that of the single layer [Fig. 10(a)], single layer andtRu=1 ?A). As the Ru thickness increases, two resonance peaks appear in theS21–fcurve. It is exciting that an ultrahigh OM FMR frequency of 20.02 GHz is present in thetRu=2.5 ?A trilayer with the AFM coupling. The fact indicates that the AFM interlayer coupling is an effective way to obtain an ultrahigh FMR frequency. In addition,a pure OM ferromagnetic resonance with a frequency of 19.42 GHz is also obtained attRu=3 ?A. For the trilayers with Ru thickness in the range of 2 ?A≤tRu≤8 ?A,the antiferromagnetic interlayer coupling exists with the OM frequency higher than the AM one. However, in the range of 9 ?A≤tRu≤14.5 ?A,the ferromagnetic interlayer coupling appears with the AM frequency becoming higher than OM frequency. WhentRu=16 ?A,the interlayer coupling type reverts to the AFM again. The oscillation of interlayer coupling is summarized in Fig.10(b).

    Fig.9. In-plane angle dependence of FMR frequency and intensity at T-mode for tRu=10-?A trilayer in various magnetic fields.

    Fig. 10. (a) Curves of scattering parameter S21 versus frequency (S21–f) along EA direction for FeCoB/Ru(tRu)/FeCoB trilayers, and (b) Ruthickness-dependent AM and OM frequencies in zero magnetic field.

    3.3. Analysis of interlayer exchange coupling coefficients

    The effect of interlayer coupling on FMR properties has been extensively investigated.[39,43–46]Like the spin–exchange interaction of electrons, the interlayer exchange coupling energy between the trilayers of the film can be expressed as[22]

    whereM1andM2are the magnetization vectors of the two ferromagnetic layers respectively,J1is the bilinear coupling coefficient, andJ2is the biquadratic coupling coefficient. IfJ1plays a dominant role, whenJ1> 0, the magnetic moments are aligned parallel to minimize the free energy, thus the ferromagnetic coupling occurs;whenJ1<0,the magnetic moments are antiparallel, and antiferromagnetic coupling is present. WhenJ2plays a dominant role andJ2< 0, when the magnetic moments are orthogonal,the free energy is minimized.

    Fig.11. Schematic diagram of FMR coordinates of FM/NM/FM trilayer.

    A schematic diagram of the FMR coordinates of the FM/NM/FM trilayers is shown in Fig.11. Supposing that the thickness of ferromagnetic layer A istA, the anisotropic field along thexdirection isHA, the magnetization isMA, and the direction can be uniquely determined byθAand?A,and so is the case for ferromagnetic layer B.Since the thickness of the non-magnetic layer is less than the critical coupling thickness,there is interlayer coupling between the two ferromagnetic layers A and B.

    Now,a case is considered here that only the applied magnetic field within the film surface is considered and the angle between the magnetic field direction and thexaxis is set to beδ, and the direction of the microwave field h is along theyaxis. For this trilayer film structure,in addition to the interlayer exchange coupling energy, the respective energy of the two ferromagnetic layers should also be considered,so the free energy per unit area of the structure can be expressed as

    Fig. 12. (a)–(e) Comparison between the simulation results and experimental results for trilayers, and (f) coupling coefficients J1 and J2 oscillating with variation of Ru thickness in middle layer. The unit 1 erg=10?7 J.

    The parameters of the film are substituted into the equation, and by setting different coupling coefficientsJ1andJ2,the calculated results are compared with the experimental ones so that the optimized coefficients are obtained. Figures 12(a)–12(e) show the comparisons between the theoretical simulation and the experimental results. The simulated coupling coefficientsJ1andJ2are summarized in Fig. 12(f). It is interesting to note that the simulation results are well consistent with the experimental ones. AttRu≤1 ?A, the FM interlayer coupling occurs. In the range of 2 ?A≤tRu≤8 ?A,J1<0 is dominant, and AFM coupling appears. In the range of 9 ?A≤tRu≤14.5 ?A,J1>0 and the coupling type changes into the FM coupling. When the Ru thickness increases to 16 ?A,the coupling type reverts to the AFM coupling again. In addition,the bilinear and biquadratic coupling(J1andJ2)are present simultaneously for the trilayers withtRu=6 ?A–8 ?A in the transition region from AFM to FM coupling[Fig.12(f)].

    4. Conclusions

    The FeCoB/Ru/FeCoB trilayers with various values of Ru thickness are prepared by a composition gradient sputtering method to realize the interlayer coupling and investigate its effect on the FMR performances. Interestingly, it is observed that the interlayer coupling oscillates with two periods from FM to AFM by varying Ru thickness. The Ru thickness dependence of two oscillation periods can be divided into four segments: 0–2, 2–8, 9–14.5, and above 16 ?A, corresponding to FM,AFM,FM,and AFM couplings,respectively. In addition, in the first AFM coupling region oftRu=2 ?A–8 ?A, the OM resonance frequency is far higher than the AM one. In the trilayer withtRu=2.5 ?A,an ultrahigh OM frequency over 20 GHz is achieved. This means that the AFM interlayer coupling is an effective way to enhance the FMR frequency. This study provides a way to control the interlayer coupling type and intensity, and therefore obtaining the excellent ultrahigh FMR performances.

    Acknowledgements

    Project supported by the National Natural Science Foundation of China(Grant Nos.51871127 and 11674187).

    猜你喜歡
    山東
    圖說(shuō)山東
    新航空(2023年9期)2023-09-18 18:59:16
    開(kāi)放的山東,乘風(fēng)前行
    金橋(2022年6期)2022-06-20 01:35:36
    聚焦鄉(xiāng)村振興的“山東作為”
    金橋(2022年4期)2022-05-05 06:10:00
    讓世界了解山東 讓山東走向世界
    走向世界(2022年3期)2022-04-19 12:38:54
    逆勢(shì)上揚(yáng)的山東,再出發(fā)
    金橋(2022年3期)2022-03-29 01:16:24
    冬奧會(huì)背后的“山東力量”
    金橋(2022年3期)2022-03-29 01:16:20
    『山東艦』入列一周年
    大運(yùn)河,行走山東
    金橋(2021年6期)2021-07-23 01:27:06
    山東電改僵局
    能源(2020年10期)2020-11-13 07:05:40
    山東濟(jì)寧卷
    狂野欧美激情性xxxx在线观看| 精品国内亚洲2022精品成人| 永久网站在线| 99久久精品热视频| 18禁在线无遮挡免费观看视频 | 2021天堂中文幕一二区在线观| 香蕉av资源在线| 免费搜索国产男女视频| 别揉我奶头 嗯啊视频| 伊人久久精品亚洲午夜| 黄片wwwwww| av在线天堂中文字幕| 一进一出抽搐动态| 99精品在免费线老司机午夜| 中文字幕av成人在线电影| 久久99热这里只有精品18| 两个人视频免费观看高清| 亚洲成a人片在线一区二区| 国产激情偷乱视频一区二区| 91久久精品电影网| 变态另类丝袜制服| 亚洲欧美日韩高清专用| 国产av麻豆久久久久久久| 亚洲国产高清在线一区二区三| 日韩欧美一区二区三区在线观看| 六月丁香七月| 久久精品国产鲁丝片午夜精品| 又黄又爽又免费观看的视频| 久久99热这里只有精品18| 免费搜索国产男女视频| 中文字幕人妻熟人妻熟丝袜美| 黄色一级大片看看| www.色视频.com| 99久久无色码亚洲精品果冻| 中文在线观看免费www的网站| 精品福利观看| 香蕉av资源在线| 一边摸一边抽搐一进一小说| 久久久a久久爽久久v久久| 小说图片视频综合网站| 国产精品久久久久久精品电影| 我要搜黄色片| 成年免费大片在线观看| 又黄又爽又免费观看的视频| 色综合亚洲欧美另类图片| 夜夜爽天天搞| 午夜久久久久精精品| 精品不卡国产一区二区三区| 十八禁网站免费在线| 99久久精品国产国产毛片| 天堂影院成人在线观看| 精品一区二区三区人妻视频| a级毛片a级免费在线| 亚洲人与动物交配视频| 在线国产一区二区在线| 国产 一区精品| 超碰av人人做人人爽久久| 在线看三级毛片| 中文字幕av在线有码专区| 嫩草影视91久久| 亚洲无线在线观看| 中出人妻视频一区二区| 欧美最新免费一区二区三区| 欧美精品国产亚洲| 麻豆乱淫一区二区| 黄色一级大片看看| 亚州av有码| 亚洲最大成人手机在线| 中文字幕av在线有码专区| 日日啪夜夜撸| 狠狠狠狠99中文字幕| 老司机福利观看| 久久久久国产精品人妻aⅴ院| 91av网一区二区| 日韩成人av中文字幕在线观看 | 热99在线观看视频| 18禁裸乳无遮挡免费网站照片| 中文在线观看免费www的网站| 成人特级黄色片久久久久久久| 久久久久久久久久黄片| 非洲黑人性xxxx精品又粗又长| 成人精品一区二区免费| 国产 一区精品| 欧美激情在线99| 久久精品久久久久久噜噜老黄 | 18禁在线播放成人免费| 中文字幕免费在线视频6| 亚洲av五月六月丁香网| 亚洲精品色激情综合| 别揉我奶头~嗯~啊~动态视频| 免费一级毛片在线播放高清视频| 亚洲乱码一区二区免费版| 亚洲av一区综合| 91精品国产九色| 少妇高潮的动态图| 国产精品人妻久久久影院| 在线免费十八禁| 波多野结衣巨乳人妻| 禁无遮挡网站| 亚洲在线自拍视频| 女同久久另类99精品国产91| 国产精品三级大全| 成年女人毛片免费观看观看9| 国产伦一二天堂av在线观看| 三级国产精品欧美在线观看| 美女cb高潮喷水在线观看| 午夜老司机福利剧场| aaaaa片日本免费| 成人亚洲精品av一区二区| 亚洲成av人片在线播放无| 亚洲人成网站在线播放欧美日韩| 2021天堂中文幕一二区在线观| 亚洲av美国av| 69人妻影院| 一进一出抽搐动态| 乱码一卡2卡4卡精品| 欧美+日韩+精品| 搞女人的毛片| 村上凉子中文字幕在线| 日韩欧美一区二区三区在线观看| or卡值多少钱| 男插女下体视频免费在线播放| 久久久a久久爽久久v久久| 国产精品国产高清国产av| 国产真实伦视频高清在线观看| 99在线人妻在线中文字幕| 日日干狠狠操夜夜爽| 国产亚洲欧美98| 国产免费男女视频| 日本免费一区二区三区高清不卡| 香蕉av资源在线| 午夜老司机福利剧场| aaaaa片日本免费| 精品人妻一区二区三区麻豆 | 久久精品91蜜桃| 97人妻精品一区二区三区麻豆| 天堂√8在线中文| 天天躁日日操中文字幕| 国产日本99.免费观看| 99久久成人亚洲精品观看| 国产成人精品久久久久久| 女生性感内裤真人,穿戴方法视频| 色吧在线观看| 观看免费一级毛片| 国产精品亚洲一级av第二区| 男人舔女人下体高潮全视频| 露出奶头的视频| 一级毛片我不卡| 女人被狂操c到高潮| av在线老鸭窝| 中文资源天堂在线| 精品国内亚洲2022精品成人| 亚洲欧美成人精品一区二区| 亚洲成av人片在线播放无| 国内精品一区二区在线观看| 国产免费一级a男人的天堂| 老司机午夜福利在线观看视频| 美女被艹到高潮喷水动态| 变态另类成人亚洲欧美熟女| 亚洲精品一区av在线观看| 欧美性猛交╳xxx乱大交人| 国产精品久久电影中文字幕| 在线观看av片永久免费下载| 成人午夜高清在线视频| 欧美最黄视频在线播放免费| 男女做爰动态图高潮gif福利片| 亚洲欧美日韩高清专用| 99久久九九国产精品国产免费| 日韩三级伦理在线观看| 欧美成人精品欧美一级黄| 欧美区成人在线视频| 有码 亚洲区| 性欧美人与动物交配| av天堂中文字幕网| 噜噜噜噜噜久久久久久91| 女的被弄到高潮叫床怎么办| 12—13女人毛片做爰片一| 午夜亚洲福利在线播放| 一级毛片aaaaaa免费看小| 美女大奶头视频| 一边摸一边抽搐一进一小说| 波多野结衣巨乳人妻| 男人舔女人下体高潮全视频| 99热6这里只有精品| 久久鲁丝午夜福利片| 国产精品,欧美在线| 中文字幕精品亚洲无线码一区| 国产精品国产高清国产av| 十八禁网站免费在线| 久久久国产成人精品二区| 国产精品亚洲一级av第二区| 日韩强制内射视频| 淫妇啪啪啪对白视频| 国产精品福利在线免费观看| 日本欧美国产在线视频| 欧美不卡视频在线免费观看| 变态另类丝袜制服| 天堂影院成人在线观看| 18禁黄网站禁片免费观看直播| 亚洲精品国产av成人精品 | 99久久精品热视频| 午夜激情福利司机影院| 日本黄色视频三级网站网址| 欧美一区二区亚洲| 国产在视频线在精品| 欧美又色又爽又黄视频| 日韩亚洲欧美综合| 国产高清不卡午夜福利| 欧美日韩乱码在线| 亚洲中文日韩欧美视频| 国产高清视频在线观看网站| 久久久国产成人精品二区| 日本-黄色视频高清免费观看| a级毛片免费高清观看在线播放| 高清毛片免费看| 国产高清视频在线播放一区| 欧美成人一区二区免费高清观看| 欧美高清成人免费视频www| 日韩欧美一区二区三区在线观看| 一级黄片播放器| 欧美区成人在线视频| 18禁在线播放成人免费| 国产av麻豆久久久久久久| 久久精品夜夜夜夜夜久久蜜豆| 国产美女午夜福利| 国产精品1区2区在线观看.| 狂野欧美激情性xxxx在线观看| 精品人妻一区二区三区麻豆 | 日韩亚洲欧美综合| 亚洲成人av在线免费| 国产精品精品国产色婷婷| 国产色爽女视频免费观看| 欧美又色又爽又黄视频| 亚洲国产精品成人久久小说 | 亚洲欧美成人综合另类久久久 | 好男人在线观看高清免费视频| 日韩,欧美,国产一区二区三区 | 色吧在线观看| 中文字幕免费在线视频6| 又粗又爽又猛毛片免费看| 中国美女看黄片| 久久久久免费精品人妻一区二区| 久久精品影院6| 欧美极品一区二区三区四区| av中文乱码字幕在线| 亚洲最大成人手机在线| 成人亚洲欧美一区二区av| 国产一区二区三区在线臀色熟女| 最近最新中文字幕大全电影3| 亚洲美女黄片视频| 国产精品美女特级片免费视频播放器| 精品熟女少妇av免费看| 久久久久国内视频| 国语自产精品视频在线第100页| 亚洲最大成人av| 国产综合懂色| 最新中文字幕久久久久| 热99re8久久精品国产| 三级男女做爰猛烈吃奶摸视频| 最近视频中文字幕2019在线8| av黄色大香蕉| 亚洲美女视频黄频| 中出人妻视频一区二区| 久久人人精品亚洲av| 麻豆成人午夜福利视频| 日本-黄色视频高清免费观看| 日日摸夜夜添夜夜爱| 波多野结衣巨乳人妻| av免费在线看不卡| 色尼玛亚洲综合影院| 亚洲真实伦在线观看| 免费观看的影片在线观看| 国产精品一区二区三区四区免费观看 | 国产亚洲欧美98| 悠悠久久av| 六月丁香七月| 精品福利观看| 欧美在线一区亚洲| 又黄又爽又免费观看的视频| 日本爱情动作片www.在线观看 | 一个人观看的视频www高清免费观看| 免费av观看视频| 天堂动漫精品| av在线老鸭窝| 美女黄网站色视频| 99久久成人亚洲精品观看| 日本色播在线视频| 97超级碰碰碰精品色视频在线观看| 在线天堂最新版资源| 亚洲欧美日韩卡通动漫| 亚洲欧美日韩东京热| 丰满乱子伦码专区| 日韩一区二区视频免费看| 免费av毛片视频| 免费看日本二区| 久久久午夜欧美精品| 亚洲欧美日韩高清专用| 色哟哟哟哟哟哟| 亚洲精品久久国产高清桃花| 免费无遮挡裸体视频| 偷拍熟女少妇极品色| 美女被艹到高潮喷水动态| 黑人高潮一二区| 亚洲图色成人| 国产高清激情床上av| 老司机午夜福利在线观看视频| 神马国产精品三级电影在线观看| 日韩 亚洲 欧美在线| 永久网站在线| 男人和女人高潮做爰伦理| 国产精品1区2区在线观看.| 69人妻影院| 国产午夜精品论理片| 一区二区三区免费毛片| 18+在线观看网站| 免费高清视频大片| 最近最新中文字幕大全电影3| 亚洲欧美成人综合另类久久久 | 国产日本99.免费观看| 22中文网久久字幕| 免费观看的影片在线观看| 变态另类成人亚洲欧美熟女| 国模一区二区三区四区视频| 欧美区成人在线视频| 18禁在线无遮挡免费观看视频 | 最近在线观看免费完整版| 国产亚洲精品久久久久久毛片| 天天躁日日操中文字幕| 黄色配什么色好看| 69人妻影院| 国产精品99久久久久久久久| 免费大片18禁| 两性午夜刺激爽爽歪歪视频在线观看| 少妇裸体淫交视频免费看高清| 国产亚洲精品综合一区在线观看| 亚洲最大成人av| 午夜视频国产福利| 狂野欧美激情性xxxx在线观看| 国产伦精品一区二区三区四那| 国产成年人精品一区二区| 中文字幕人妻熟人妻熟丝袜美| 婷婷六月久久综合丁香| 精品人妻一区二区三区麻豆 | 如何舔出高潮| 色噜噜av男人的天堂激情| 一级av片app| 久久人人精品亚洲av| 麻豆乱淫一区二区| 亚洲美女黄片视频| 99久国产av精品| 久久人人精品亚洲av| 国产视频内射| 亚洲美女黄片视频| 99久国产av精品| 久久国产乱子免费精品| 色av中文字幕| 国产伦精品一区二区三区视频9| 成熟少妇高潮喷水视频| 久久精品夜夜夜夜夜久久蜜豆| 成人亚洲精品av一区二区| av国产免费在线观看| 一级av片app| 亚洲精品日韩av片在线观看| 蜜桃亚洲精品一区二区三区| 美女大奶头视频| 麻豆乱淫一区二区| 亚洲国产精品sss在线观看| 又爽又黄无遮挡网站| 亚洲成人精品中文字幕电影| 蜜桃亚洲精品一区二区三区| 精品国产三级普通话版| 国产精品永久免费网站| av免费在线看不卡| 中文字幕久久专区| 色哟哟·www| 美女被艹到高潮喷水动态| 精品久久国产蜜桃| 亚洲成av人片在线播放无| 久久久精品欧美日韩精品| 亚洲成av人片在线播放无| 舔av片在线| 日韩在线高清观看一区二区三区| 日本免费a在线| 熟妇人妻久久中文字幕3abv| 狠狠狠狠99中文字幕| 黄色一级大片看看| 一级毛片我不卡| 亚洲中文字幕日韩| 别揉我奶头~嗯~啊~动态视频| 老熟妇仑乱视频hdxx| 最近2019中文字幕mv第一页| 亚洲乱码一区二区免费版| 男人狂女人下面高潮的视频| 亚洲欧美成人综合另类久久久 | 晚上一个人看的免费电影| 亚洲成人中文字幕在线播放| 高清毛片免费看| 久久久久久久久大av| 国产 一区 欧美 日韩| 色吧在线观看| 一级毛片aaaaaa免费看小| 成人特级av手机在线观看| 亚洲av中文字字幕乱码综合| 欧美一区二区亚洲| 99久久九九国产精品国产免费| 毛片一级片免费看久久久久| 九九在线视频观看精品| 久久久色成人| 久久精品人妻少妇| 亚洲一区高清亚洲精品| 3wmmmm亚洲av在线观看| 亚洲天堂国产精品一区在线| 十八禁网站免费在线| 国产精品野战在线观看| 乱人视频在线观看| 国产精品国产高清国产av| 六月丁香七月| 精品一区二区三区人妻视频| 少妇熟女欧美另类| eeuss影院久久| 精品99又大又爽又粗少妇毛片| 亚洲欧美成人综合另类久久久 | 亚洲av电影不卡..在线观看| 免费av毛片视频| 成人美女网站在线观看视频| 淫秽高清视频在线观看| 日韩,欧美,国产一区二区三区 | 国产高清有码在线观看视频| av福利片在线观看| 最近在线观看免费完整版| 91午夜精品亚洲一区二区三区| 麻豆精品久久久久久蜜桃| 亚洲欧美日韩无卡精品| 精品99又大又爽又粗少妇毛片| 久久精品国产清高在天天线| 国产av麻豆久久久久久久| 成人漫画全彩无遮挡| 黄色配什么色好看| 美女cb高潮喷水在线观看| 欧美一区二区精品小视频在线| 99热全是精品| 一区福利在线观看| 久久欧美精品欧美久久欧美| 国产日本99.免费观看| 美女免费视频网站| 国产在视频线在精品| 免费高清视频大片| av在线亚洲专区| 女人十人毛片免费观看3o分钟| 一个人看的www免费观看视频| 俺也久久电影网| 1000部很黄的大片| 最新在线观看一区二区三区| 国产精品av视频在线免费观看| 国产高清三级在线| 国产一区二区三区在线臀色熟女| 大香蕉久久网| 久久午夜亚洲精品久久| 婷婷精品国产亚洲av在线| 中出人妻视频一区二区| 美女黄网站色视频| 成人精品一区二区免费| 亚洲欧美日韩卡通动漫| 成年女人看的毛片在线观看| 久久精品夜色国产| 欧美bdsm另类| 午夜精品一区二区三区免费看| 日韩强制内射视频| 成年版毛片免费区| 亚洲av免费高清在线观看| 国产三级中文精品| 午夜福利成人在线免费观看| 亚洲av美国av| 尾随美女入室| 美女内射精品一级片tv| 国产免费一级a男人的天堂| 久久99热6这里只有精品| 国内揄拍国产精品人妻在线| 联通29元200g的流量卡| 男女之事视频高清在线观看| 国产视频一区二区在线看| 可以在线观看的亚洲视频| 美女大奶头视频| 乱码一卡2卡4卡精品| 一级毛片电影观看 | 欧美国产日韩亚洲一区| 久久久久久久久久黄片| 久久亚洲国产成人精品v| 亚洲aⅴ乱码一区二区在线播放| 中文亚洲av片在线观看爽| 乱系列少妇在线播放| 国产 一区精品| 亚洲第一电影网av| 国产一区二区激情短视频| 天天一区二区日本电影三级| 国产亚洲av嫩草精品影院| 亚洲av中文av极速乱| 校园春色视频在线观看| 亚洲熟妇熟女久久| 久久久久国产网址| 亚洲av免费高清在线观看| 日本与韩国留学比较| 又爽又黄a免费视频| 久久久精品94久久精品| h日本视频在线播放| 成人性生交大片免费视频hd| 色噜噜av男人的天堂激情| 99热这里只有是精品50| 国产精品精品国产色婷婷| .国产精品久久| 亚洲成人久久爱视频| 国产不卡一卡二| 日韩大尺度精品在线看网址| 嫩草影院新地址| 全区人妻精品视频| 韩国av在线不卡| 久久99热这里只有精品18| 天堂av国产一区二区熟女人妻| 亚洲欧美日韩卡通动漫| 国产高潮美女av| 国产精品伦人一区二区| 亚洲熟妇中文字幕五十中出| 天天一区二区日本电影三级| 在现免费观看毛片| 深夜a级毛片| 亚洲av成人精品一区久久| 日韩欧美免费精品| 在线天堂最新版资源| 久久99热6这里只有精品| 我的女老师完整版在线观看| 日韩成人伦理影院| 男人的好看免费观看在线视频| 自拍偷自拍亚洲精品老妇| 中文在线观看免费www的网站| 亚洲最大成人av| 欧美区成人在线视频| 97超级碰碰碰精品色视频在线观看| 99热网站在线观看| av在线亚洲专区| 美女cb高潮喷水在线观看| 亚洲乱码一区二区免费版| 国产高清三级在线| 搡老妇女老女人老熟妇| 亚洲中文字幕一区二区三区有码在线看| 女人被狂操c到高潮| 国产一区亚洲一区在线观看| 熟妇人妻久久中文字幕3abv| 久久久色成人| 少妇被粗大猛烈的视频| 国产激情偷乱视频一区二区| 久久天躁狠狠躁夜夜2o2o| 午夜福利在线在线| 乱码一卡2卡4卡精品| 国产精品女同一区二区软件| 精品一区二区三区视频在线观看免费| 亚洲一区高清亚洲精品| 欧美精品国产亚洲| 国产精品国产高清国产av| 亚洲成人久久爱视频| 久久婷婷人人爽人人干人人爱| 看黄色毛片网站| 久久午夜福利片| 日产精品乱码卡一卡2卡三| 高清毛片免费看| 嫩草影院精品99| 久久精品91蜜桃| 精品午夜福利视频在线观看一区| 有码 亚洲区| .国产精品久久| 久久99热6这里只有精品| 深夜精品福利| 婷婷亚洲欧美| 国产中年淑女户外野战色| 我的女老师完整版在线观看| 搞女人的毛片| 国产真实乱freesex| 久久亚洲精品不卡| 亚洲国产日韩欧美精品在线观看| 久久国内精品自在自线图片| 久久精品国产自在天天线| 成人精品一区二区免费| 午夜免费激情av| 婷婷色综合大香蕉| a级一级毛片免费在线观看| 亚洲高清免费不卡视频| 日本与韩国留学比较| 免费观看精品视频网站| 久久韩国三级中文字幕| 日产精品乱码卡一卡2卡三| 国产成人a区在线观看| 丝袜美腿在线中文| 婷婷精品国产亚洲av在线| 精品一区二区三区av网在线观看| 岛国在线免费视频观看| 男人舔奶头视频| 十八禁国产超污无遮挡网站| 亚洲av熟女| 久久久午夜欧美精品| 亚洲在线自拍视频| 99久久无色码亚洲精品果冻| 免费看a级黄色片| 青春草视频在线免费观看| 六月丁香七月| 国产一区二区三区av在线 | 国产三级中文精品| 十八禁国产超污无遮挡网站| 日日摸夜夜添夜夜爱| av天堂在线播放| 亚洲三级黄色毛片| 一区二区三区免费毛片| 成人三级黄色视频| 波多野结衣巨乳人妻| 免费观看的影片在线观看| 一区福利在线观看| 国产午夜精品论理片|