• <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 ?

    Controllable high Curie temperature through 5d transition metal atom doping in CrI3

    2024-01-25 07:30:04XuebingPeng彭雪兵MingsuSi司明蘇andDaqiangGao高大強(qiáng)
    Chinese Physics B 2024年1期

    Xuebing Peng(彭雪兵), Mingsu Si(司明蘇), and Daqiang Gao(高大強(qiáng)),?

    1School of Physical Science and Technology,Lanzhou University,Lanzhou 730000,China

    2School of Materials and Energy,Lanzhou University,Lanzhou 730000,China

    Keywords: ferromagnetism,magnetic anisotropy energy,Curie temperature,half-metal

    1.Introduction

    Although two-dimensional (2D) materials have been explored for more than a decade,magnetic order rarely survives in atomically thin films due to thermal fluctuations.[1,2]The realization of 2D magnets is a big challenge.An early strategy was to introduce local defect states with magnetic elements into non-magnetic materials.[3–6]The magnetism introduced by this method is short-range.A new method to achieve lowdimensional ferromagnets is to use intrinsic magnetic order.In 2017, monolayer CrI3and few-layer Cr2Ge2Te6were simultaneously reported.[7,8]Immediately afterwards, in 2018,Denget al.successfully prepared monolayer Fe3GeTe2with intrinsic ferromagnetism.[9]These works opened the door for the study of 2D magnetic materials and provided a novel material platform for the future development of low-dimensional spintronics.

    CrI3as a layered magnetic material was first systematically studied by Dillon and Olson[10]and realized in the monolayer limit by Huanget al.[7]A spin-orientation-controlled band structure offers the opportunity for the study of second harmonics in solid state physics.[13,14]Due to its special crystal structure,CrI3has a topologically protected spin magnetic moment[15]as well as Kitaev interaction induced by shared edge I?.[16]With a strong layer-dependent effect,the magnetic ground state can be changed from ferromagnetic(FM)to antiferromagnetic(AFM)as the monolayer becomes a bilayer.[17]The excellent magnetism of CrI3makes it potentially promising for applications in the field of spintronics.Most research is based on the intrinsic magnetism of CrI3.However,the Curie temperature(Tc)of CrI3is only 45 K,[18]which severely limits practical applications.Thus, increasing theTcof CrI3is a focus of research.

    The magnetism of monolayer CrI3has been modulated by strain,[19,20]carrier doping,[21]defect introduction,[22,23]applied electric field[24]and surface adsorption.[25–27]For example,Guoet al.adsorbed Li atoms on the surface to semimetallize CrI3and increaseTc.[28]Yanget al.used Sc atoms to dope CrI3and increasedTcfrom 47 K to 131 K.[29]The gain or loss of electrons causes an increase in the magnetic moment of Cr, which eventually increasesTc.In fact, the above methods are not particularly effective ways to increaseTcbecause Li and Sc atoms have almost no magnetic moment in a honeycomb lattice.Recently, Birgeneau’s group successfully prepared Fe5GeTe2,which has a higherTc(over 400 K)than Fe3GeTe2.The underlying physics originates from the increasing coordination number of the Fe ion.[30]Based on the above ideas,we chose 5d transition metal(TM)atoms to dope CrI3,because 5d TM atoms with a larger spin–orbit coupling(SOC) may increase the magnetic anisotropy energy (MAE)to stabilize long-range FM order.

    In this work, we investigate the crystal stability, MAE,Tc,FM stability and electronic properties of TM@CrI3based on first-principles calculations.Formation energy and phonon spectra calculations show that TM@CrI3is thermodynamically stable, and the absence of imaginary modes in phonon spectra indicates that TM@CrI3monolayers (TM=Hf, Ta,W, Re and Os) are also dynamically stable.Due to the increase in magnetic moment induced by the doping of TM atoms,TM@CrI3has a higherTcthrough Monte–Carlo(MC)simulation.Among these,Tcof W@CrI3reaches 254 K.By further increasing the doping concentration of W atoms, aTcabove room temperature can be achieved.Intriguingly,a large MAE for W@CrI3can stabilize long-range FM order.Moreover,FM stability of TM@CrI3is enhanced.Most TM@CrI3change from a semiconductor to a half-metal.These results provide knowledge relevant to potential applications of CrI3monolayers in spintronics.

    2.Computational details

    We use the framework of density functional theory as implemented in the Viennaab initiosimulation package to perform first-principles calculations.[31,32]The Monkhorst–Pack scheme of 5×5×1k-point sampling in the entire Brillouin zone (BZ) was used to perform momentum space integration for a 2×2×1 TM@CrI3supercell.[33]MAE was calculated with a 12×12×1k-point mesh.The plane-wave cutoff energy was set to 500 eV.The generalized gradient approximation with the Perdew–Burke–Ernzerhof realization was used for the exchange correlation functional.[34]The Hellmann–Feynman forces acting on each atom were entirely relaxed during structural optimization until they were less than 10?3eV·?A?1;the electronic convergence requirement was set to 10?7eV.Since the system is a 2D nanosheet,a vacuum region of 20 ?A along the direction perpendicular to the surface of the nanosheet was introduced to avoid interference between the periodic images.A 30×30×1 supercell was used to simulateTcbased on the MC method.[35]

    3.Results and discussion

    Monolayer CrI3possesses the space group ofp-31m(No.162).Cr3+ions are sandwiched by octahedra formed by shared-edge I?ions and form a hexagonal honeycomb structure, as shown in Fig.1(a).The optimized lattice constant isa=b=7.00 ?A.The Cr3+–I?and Cr3+–Cr3+bond distances are 2.7 ?A and 4.0 ?A, respectively.The magnetic moment of each Cr3+ion is 3.06μB.The band structure of CrI3is displayed in Fig.1(b).The valence band maximum and the conduction band minimum appear for the spin-up channel,giving a band gap of 1.21 eV.All these results are in good agreement with previously reported results.[29,36]Here, we dope CrI3with one 5d TM atom, introducing it into the interstitial hollow position of a 2×2×1 supercell,as shown in Fig.1(c).

    Fig.1.(a)Top(top panel)and side(bottom panel)views of the crystal structure of CrI3,where H represents the hollow position.(b)Calculated band structure of CrI3.The Fermi energy is set to 0 eV.(c)Crystal structure of a transition metal(TM)atom introduced into the hollow position.(d)Formation energies of TM@CrI3.(e)Calculated Curie temperature(Tc)of TM@CrI3 and host CrI3.(f)Magnetic moment and specific heat of W@CrI3 versus temperature from Monte–Carlo simulation.

    To reveal the thermodynamic stability of atomic doping, we calculate the formation energy, which is defined asFf=Edop?ECrI3?μTMwhereEdopis the total energy of TM@CrI3,ECrI3is the total energy of CrI3andμTMis the chemical potential of the TM atom.As shown in Fig.1(d),the formation energies of all TM@CrI3are negative, indicating that all are thermodynamically stable.We also calculate the phonon dispersion over a 2×2×1 supercell using the PHONOPY package,[37]which is based on density functional perturbation theory.[38]The absence of imaginary modes in the entire BZ is displayed in Figs.S1(a)–S1(e),indicating that monolayer TM@CrI3(TM=Hf, Ta, W, Re and Os) are dynamically stable.However, doping with Ir, Pt and Au atoms is not dynamically stable as the imaginary frequencies appear near theΓpoint(Figs.S1(f)–S1(h)).

    To estimateTcof TM@CrI3,we calculate exchange couplings between magnetic atoms via the Heisenberg exchange interaction,H=∑i,δ JNSi·Sδ, whereJNrepresents the exchange couplings between magnetic atoms,iis the magnetic atomic site andδrepresents the nearest neighbor distance.Siis the spin quantum number.Here, we mainly consider the nearest and next-nearest exchange couplings between Cr3+and Cr3+ions as well as the nearest exchange coupling between Cr3+ions and the TM atom, denoted asJ1,J2andJ3,respectively.J3is only considered for W and the Ta atoms with the larger magnetic moments.One FM and three AFM configurations(N′eel,zigzag and stripy)are used in the calculations of exchange coupling, as shown in Fig.3(a).The three magnetic coupling constants can be extracted from the following equations:

    whereSA,SBandSCare the spin operators of magnetic ions on A, B and C sites.The exchange coupling constants are given in Table S1.

    Based on the 2D Ising model, we employ Metropolis Monte–Carlo(MC)simulation to studyTc.Figure 1(e)shows theTcof TM@CrI3.Tcof the host CrI3is also calculated to be 45 K, which is in line with the result reported in previous work.[7]In TM@CrI3,Tcis significantly increased.Tcof Au@CrI3is about 64 K,which is slightly higher than that of the host CrI3.Tcof W@CrI3reaches 254 K, nearly six times higher than that of the host CrI3,and is much increased in comparison with 3d TM@CrI3.[29]Meanwhile,in Fig.1(f)variation of the average magnetic moment and specific heat of W@CrI3with temperature is shown.We further exploredTcfor W@CrI3for different doping concentrations: 5.9%and 8.6% represent 2×2×1 CrI3doped with two and three W atoms, respectively(Fig.S4).It is pleasing to note thatTcof CrI3is significantly improved with increasing W doping concentration.As shown in Fig.2(a),at a doping concentration of 5.9%,Tcincreases from 254 K to 306 K,which is above room temperature.With continuing increase in the doping concentration,Tcof W@CrI3is increased to 348 K(Fig.2(b)).

    Fig.2.Magnetic moment and specific heat versus temperature for doping concentrations of(a)5.9%and(b)8.6%for W@CrI3.

    To account for variation ofTc,we calculated the exchange energy, which is defined asEAFM–EFM.Here, zigzag-AFM is chosen as a reference due to its lower energy.Among the TM@CrI3, the W atom has the highest exchange energy, the Ta atom the next and the Au atom the least,but their exchange energy is greater than that of CrI3,as shown in Fig.3(b).The pattern of variation of exchange energy is consistent withTc.Similarly, the magnetic moments of TM atoms also show the same pattern of variation.For example, the W atom with the largest magnetic moment has the highestTc(Fig.3(c)).The Au atom has almost no magnetic moment,and the increase inTcis not significant.This result indicates thatTcis related to the magnetic moments of TM atoms.The magnetic moments of TM atoms increase the exchange coupling and coordination number between the magnetic atoms.Further, according to a mean-field treatment, results for the magnetic transition temperature follow, whereZNNandJNNare the coordination number and exchange coupling of magnetic atoms,respectively.[9,39]The larger the magnetic atomic coordination number, the exchange coupling and the magnetic moment,the higher the evaluatedTc.Therefore,the magnetic moments induced by doping with TM atoms can increaseTc.

    Fig.3.(a)Four magnetic configurations:ferromagnetic(FM),N′eel antiferromagnetic(AFM),zigzag AFM and stripy AFM.(b)The calculated exchange energy of TM@CrI3 and the host CrI3.(c)The magnetic moments of TM atoms and Cr3+ ions(TM,transition metal).

    Next,we discuss the underlying physics of the W atomic magnetic moment in W@CrI3.The spin-density distribution shows that the total magnetic moment stems from the Cr atoms and the W atom(Fig.4(a)).The W atom tends to lose the partial electrons of the outermost electron shell(5d46s2)through strong electronegative action around I?ions, and picks up a magnetic moment of about 2μB.We calculated the Bader charge of W@CrI3,where the W atom loses 0.6eand every I?ion gains 0.11e(Table S2).In the projected density of states,d-resolved orbitals of the W atom have a large spin polarization and hybridization(Fig.4(b)).Both the dxzand dyzorbitals are occupied by a fractional electron, and contribute 0.15μBand 0.14μB,respectively.In contrast,the dz2orbital with more spin-up electrons has a magnetic moment of 1.04μB.This is because the dz2orbital rarely overlaps with the p orbitals of the surrounding I?ions.The dx2?y2and dxyorbitals protected by C3symmetry are degenerate below the Fermi level, and their magnetic moments are 0.35μB.Furthermore, the magnitude of magnetic moments can be understood from the asymmetry of spin polarization below the Fermi level in the density of states(DOS)of TM atoms,as shown in Figs.4(c)–4(f).For example,the spin polarized asymmetry of the Hf atom is weaker than that of the Ta atom, so the magnetic moment of the Ta atom is larger.Similarly, the W atom has a larger spin polarized asymmetry than the Ta atom,leading to a larger value for the W atom.The Os atom has the weakest asymmetry.The W atom therefore has the largest magnetic moment.For low-dimensional materials, a large MAE driven by SOC would resist the thermal fluctuation to stabilize the longrange FM order.Due to the large SOC of 5d TM atoms,the induced MAE would be large, and is defined asEMAE=E(100)?E(001).Positive or negative values of MAE represent that the magnetic easy axis is along the out-of-plane or inplane direction, respectively.In Table 1, the magnetic easy axis of TM@CrI3(TM=Hf, Ta, W, Re and Ir) is along the out-of-plane direction: Re@CrI3has the largest MAE,which mainly originates from the Re atom.The magnetic easy axis for doping with Os,Pt and Au atoms is along the in-plane direction.Except for Os,the absolute values of MAE after doping are enhanced with respect to CrI3, whose MAE is about 0.804 meV.[20]Therefore,doping with TM atoms can enhance the MAE of CrI3.

    Fig.4.(a) The spin density distribution of W@CrI3 and (b) projected density of states (PDOS) of the W atom.Density of states (DOS) of(c) Hf, (d) W, (e) Ta and (f) Os atoms in TM@CrI3.The positive and negative values of DOS represent spin-up and spin-down channels,respectively.The Fermi energy is set to 0 eV.

    Table 1.The MAE(EMAE)in TM@CrI3.The contribution from Cr,I and TM atoms is also listed.The unit is meV.

    We now discuss the FM stability of TM@CrI3.The FM coupling of monolayer CrI3can be understood by the Goodenough–Kanamori–Anderson model as a competition between two exchange interactions: a direct exchange interaction between Cr3+ions by electron hopping and a superexchange between the Cr3+ions mediated by intermediate nonmagnetic I?ions.As schematically shown in Fig.5(a), stable AFM coupling depends sensitively on the distancedbetween Cr3+ions.Stable FM coupling is dominated by superexchange interactions and is controlled by theθof Cr3+–I?–Cr3+ions.Except for the Ta atom,dof Cr3+–Cr3+after doping is increased with respect to the host CrI3(Fig.5(b)),indicating that AFM coupling of direct exchange is weakened.Theθfor all TM@CrI3is decreased,and is close to 90°,giving rise to stronger FM stability.

    Fig.6.The band structure of TM@CrI3 (TM=Ta,W,Os,Ir,Pt,Au).The Fermi energy level EF is set to 0 eV.

    Electronic structure is a key concern in the study of physical properties.We display the band structure of TM@CrI3(TM=Ta, W, Os, Ir, Pt, Au) in Fig.6.Because of the gain or loss of valence electrons (Table S3), the impurity energy levels are induced in the band structure.Therefore,the energy bands of TM@CrI3(TM=Ta,W,Os,Ir,Pt)cross the Fermi energy level to change from semiconductors to half-metals.Hf@CrI3and Re@CrI3are also half-metals (Fig.S6).Such materials have promising applications in advanced magnetic recording,magnetic storage,high-efficiency magnetic sensors,spin-emitting diodes and many other fields.[40]In particular,for TM@CrI3(TM=W, Os, Ir), the band gaps of the spindown channel are greater than 1.5 eV, which prevents thermal activation effects from exciting the forbidden carriers to reduce the polarization rate.[41]Au@CrI3is a semiconductor because the Au atom has almost no gain or loss of electrons.

    4.Conclusions

    In summary, we have performed a systematic study of TM@CrI3through the combination of a first-principles method and MC simulation.All TM@CrI3are thermodynamically stable due to their negative formation energy, and the absence of imaginary modes in the phonon spectra indicates that TM@CrI3monolayers(TM=Hf,Ta,W,Re and Os)are also dynamically stable.Tcof TM@CrI3is increased, with a highest value of 254 K for W@CrI3.As the doping concentration of W atoms is increased to 8.6%,Tcis increased to above room temperature(348 K).Interestingly,W@CrI3has a large MAE of 4.999 meV to stabilize long-range FM order.Furthermore, the FM stability of TM@CrI3is enhanced.Except for doping with Au atoms,TM@CrI3become half-metallic.It is hoped that these results will provide theoretical guidance for experimentally tuning MAE,Tcand electronic structure.

    人妻久久中文字幕网| 亚洲国产高清在线一区二区三| 两个人看的免费小视频| 99久久99久久久精品蜜桃| 国产免费男女视频| 18+在线观看网站| 国产毛片a区久久久久| 国内精品美女久久久久久| 一级黄色大片毛片| 内地一区二区视频在线| 日本撒尿小便嘘嘘汇集6| 亚洲最大成人手机在线| 一夜夜www| 亚洲国产欧美人成| 一a级毛片在线观看| 男人舔奶头视频| 1000部很黄的大片| 变态另类成人亚洲欧美熟女| 757午夜福利合集在线观看| 国产熟女xx| 一区二区三区高清视频在线| 久久天躁狠狠躁夜夜2o2o| 欧美成人一区二区免费高清观看| 在线观看美女被高潮喷水网站 | 中亚洲国语对白在线视频| 亚洲av美国av| 男女下面进入的视频免费午夜| 亚洲 欧美 日韩 在线 免费| 免费无遮挡裸体视频| 村上凉子中文字幕在线| 国产成人啪精品午夜网站| 桃红色精品国产亚洲av| 国产伦人伦偷精品视频| 免费看美女性在线毛片视频| 日韩免费av在线播放| 精品一区二区三区视频在线 | 免费在线观看成人毛片| 国内精品久久久久久久电影| 亚洲黑人精品在线| 欧美日韩乱码在线| 90打野战视频偷拍视频| 国产免费一级a男人的天堂| 免费观看精品视频网站| 亚洲在线观看片| 欧美最黄视频在线播放免费| 啦啦啦韩国在线观看视频| 岛国在线观看网站| 精品一区二区三区视频在线观看免费| 91字幕亚洲| 国内少妇人妻偷人精品xxx网站| 老司机福利观看| 级片在线观看| 蜜桃亚洲精品一区二区三区| 亚洲av中文字字幕乱码综合| 成人国产综合亚洲| 2021天堂中文幕一二区在线观| 午夜a级毛片| 婷婷六月久久综合丁香| 精品乱码久久久久久99久播| 亚洲精品色激情综合| 国产免费av片在线观看野外av| 88av欧美| 色噜噜av男人的天堂激情| 精品国产美女av久久久久小说| 久久婷婷人人爽人人干人人爱| 99精品欧美一区二区三区四区| 99热只有精品国产| xxx96com| 久久这里只有精品中国| 国产真实伦视频高清在线观看 | 丰满的人妻完整版| 97超视频在线观看视频| www日本在线高清视频| 美女免费视频网站| 国产成人福利小说| 国产爱豆传媒在线观看| 日韩欧美 国产精品| 免费av不卡在线播放| 国产精品久久久久久久电影 | 久久国产乱子伦精品免费另类| 又紧又爽又黄一区二区| 夜夜躁狠狠躁天天躁| 亚洲av成人精品一区久久| 中文字幕久久专区| av专区在线播放| 一个人看视频在线观看www免费 | 国产精品女同一区二区软件 | 小蜜桃在线观看免费完整版高清| 嫁个100分男人电影在线观看| 亚洲美女黄片视频| 国内久久婷婷六月综合欲色啪| 国产在线精品亚洲第一网站| 精品不卡国产一区二区三区| 欧美又色又爽又黄视频| 成人三级黄色视频| 欧美黄色片欧美黄色片| а√天堂www在线а√下载| 亚洲精华国产精华精| 久久天躁狠狠躁夜夜2o2o| 99久久综合精品五月天人人| 国产高清激情床上av| 国产黄a三级三级三级人| 亚洲成人精品中文字幕电影| 欧美又色又爽又黄视频| 亚洲激情在线av| 最好的美女福利视频网| 国产精品久久久久久亚洲av鲁大| 欧美+亚洲+日韩+国产| 国产一区二区三区视频了| 一a级毛片在线观看| 久久香蕉国产精品| 免费看十八禁软件| 午夜激情福利司机影院| 国产aⅴ精品一区二区三区波| 欧美绝顶高潮抽搐喷水| 12—13女人毛片做爰片一| 久久精品国产自在天天线| 亚洲精品美女久久久久99蜜臀| 久久亚洲真实| 18禁在线播放成人免费| 亚洲最大成人手机在线| 国产久久久一区二区三区| 男女那种视频在线观看| 午夜福利欧美成人| www.色视频.com| www.999成人在线观看| 男女之事视频高清在线观看| 91麻豆av在线| 特级一级黄色大片| 最好的美女福利视频网| 欧美性感艳星| 国产淫片久久久久久久久 | 三级国产精品欧美在线观看| 91久久精品电影网| 黄色女人牲交| 美女大奶头视频| 色在线成人网| 国产精品av视频在线免费观看| 国产精品精品国产色婷婷| 欧美成人一区二区免费高清观看| 国产单亲对白刺激| 中文字幕高清在线视频| 一进一出抽搐gif免费好疼| 久久香蕉精品热| 精品福利观看| 无遮挡黄片免费观看| 亚洲精品色激情综合| 欧美zozozo另类| 国产成人av教育| 精品一区二区三区av网在线观看| 亚洲午夜理论影院| 激情在线观看视频在线高清| 无人区码免费观看不卡| 欧美又色又爽又黄视频| 久久精品夜夜夜夜夜久久蜜豆| 天堂√8在线中文| 免费看美女性在线毛片视频| 桃色一区二区三区在线观看| 小蜜桃在线观看免费完整版高清| 此物有八面人人有两片| 国产亚洲欧美在线一区二区| 十八禁人妻一区二区| 国产精品嫩草影院av在线观看 | 国产色爽女视频免费观看| 亚洲国产欧美网| 婷婷精品国产亚洲av| 亚洲自拍偷在线| 90打野战视频偷拍视频| 一进一出抽搐动态| 国产激情欧美一区二区| 国产乱人伦免费视频| 中文亚洲av片在线观看爽| 伊人久久大香线蕉亚洲五| 免费av毛片视频| 久久6这里有精品| 在线观看免费午夜福利视频| 国产探花在线观看一区二区| 欧美三级亚洲精品| 国产主播在线观看一区二区| 99国产综合亚洲精品| 在线观看日韩欧美| 观看免费一级毛片| 免费无遮挡裸体视频| 久久国产乱子伦精品免费另类| 亚洲无线在线观看| 精品熟女少妇八av免费久了| 日本三级黄在线观看| 每晚都被弄得嗷嗷叫到高潮| 69人妻影院| 国产成人av激情在线播放| 国产三级在线视频| 好男人在线观看高清免费视频| 搞女人的毛片| 国产一区二区在线av高清观看| 欧美成人免费av一区二区三区| 国产99白浆流出| 免费看美女性在线毛片视频| 美女被艹到高潮喷水动态| 国产不卡一卡二| 一级作爱视频免费观看| 一级黄色大片毛片| 69人妻影院| 免费在线观看日本一区| 香蕉av资源在线| av片东京热男人的天堂| 12—13女人毛片做爰片一| 久久6这里有精品| 99精品在免费线老司机午夜| 免费av毛片视频| 日本撒尿小便嘘嘘汇集6| 九九在线视频观看精品| 免费大片18禁| 天堂av国产一区二区熟女人妻| 精品国产三级普通话版| 狂野欧美白嫩少妇大欣赏| 成年版毛片免费区| 亚洲精品国产精品久久久不卡| 色av中文字幕| 国产野战对白在线观看| 免费观看的影片在线观看| 欧美绝顶高潮抽搐喷水| 中文字幕熟女人妻在线| 中文在线观看免费www的网站| 久久久久亚洲av毛片大全| 18禁裸乳无遮挡免费网站照片| 国产成人影院久久av| 在线播放无遮挡| 久久中文看片网| 桃色一区二区三区在线观看| 国产乱人视频| tocl精华| 久久久久国产精品人妻aⅴ院| 久久香蕉国产精品| 久久久精品大字幕| 国产欧美日韩一区二区三| 欧美色欧美亚洲另类二区| 成年女人看的毛片在线观看| 中亚洲国语对白在线视频| 久久精品国产综合久久久| 久久中文看片网| 国产精品久久久久久久久免 | 精品久久久久久,| 久久九九热精品免费| 欧美绝顶高潮抽搐喷水| 最近视频中文字幕2019在线8| 久久久久精品国产欧美久久久| 最好的美女福利视频网| 操出白浆在线播放| 三级国产精品欧美在线观看| 久久天躁狠狠躁夜夜2o2o| 好看av亚洲va欧美ⅴa在| 男女床上黄色一级片免费看| 级片在线观看| 亚洲国产精品999在线| 在线观看免费午夜福利视频| 三级国产精品欧美在线观看| 国产精品久久久久久人妻精品电影| 免费一级毛片在线播放高清视频| www.999成人在线观看| 内地一区二区视频在线| 中文字幕人成人乱码亚洲影| 美女高潮的动态| 91久久精品电影网| 亚洲欧美日韩高清专用| 一区二区三区激情视频| 国模一区二区三区四区视频| 国产亚洲精品一区二区www| 97超视频在线观看视频| 亚洲avbb在线观看| 一级a爱片免费观看的视频| 狂野欧美白嫩少妇大欣赏| 精品国产亚洲在线| 国产精品久久久久久人妻精品电影| 一区二区三区国产精品乱码| 国产精品三级大全| 啦啦啦韩国在线观看视频| 精品国产美女av久久久久小说| 国产单亲对白刺激| 日韩成人在线观看一区二区三区| 亚洲人与动物交配视频| av在线蜜桃| 女人十人毛片免费观看3o分钟| 亚洲成av人片在线播放无| 日日干狠狠操夜夜爽| 亚洲人成电影免费在线| 久久香蕉精品热| 女人十人毛片免费观看3o分钟| 亚洲午夜理论影院| 精品久久久久久久毛片微露脸| 人妻丰满熟妇av一区二区三区| 久久婷婷人人爽人人干人人爱| www国产在线视频色| 欧美又色又爽又黄视频| 精品一区二区三区视频在线 | 三级毛片av免费| 亚洲 欧美 日韩 在线 免费| 日日干狠狠操夜夜爽| 亚洲成av人片在线播放无| 国产黄a三级三级三级人| 久久人妻av系列| 一级a爱片免费观看的视频| 免费在线观看亚洲国产| 99国产极品粉嫩在线观看| av女优亚洲男人天堂| 亚洲人成网站在线播放欧美日韩| 性色avwww在线观看| 手机成人av网站| 搡老妇女老女人老熟妇| 欧美乱色亚洲激情| 叶爱在线成人免费视频播放| 亚洲中文日韩欧美视频| 国产精品爽爽va在线观看网站| 久久久久久久亚洲中文字幕 | 日本一二三区视频观看| 日本黄色视频三级网站网址| 欧美成人性av电影在线观看| 国产亚洲精品综合一区在线观看| 综合色av麻豆| 午夜免费男女啪啪视频观看 | 可以在线观看毛片的网站| 国产91精品成人一区二区三区| 亚洲久久久久久中文字幕| 一级a爱片免费观看的视频| 日本黄色片子视频| 精品久久久久久,| 97超级碰碰碰精品色视频在线观看| 久久久久久九九精品二区国产| 久久午夜亚洲精品久久| 国产一区二区三区视频了| 亚洲五月婷婷丁香| 亚洲中文字幕一区二区三区有码在线看| 午夜老司机福利剧场| 精品福利观看| 一区二区三区免费毛片| 国产亚洲精品久久久久久毛片| 中亚洲国语对白在线视频| 手机成人av网站| 久久久久久久精品吃奶| 国产精品一区二区三区四区免费观看 | 国产91精品成人一区二区三区| 操出白浆在线播放| 又黄又粗又硬又大视频| 国产伦精品一区二区三区视频9 | 色尼玛亚洲综合影院| 日韩欧美国产一区二区入口| 亚洲欧美一区二区三区黑人| 淫妇啪啪啪对白视频| 国内少妇人妻偷人精品xxx网站| 欧美性感艳星| 日韩欧美国产在线观看| ponron亚洲| 日本 欧美在线| 最后的刺客免费高清国语| 在线免费观看不下载黄p国产 | 老熟妇乱子伦视频在线观看| 男人舔女人下体高潮全视频| 国产伦人伦偷精品视频| 日本在线视频免费播放| 悠悠久久av| 色综合站精品国产| av黄色大香蕉| 人妻夜夜爽99麻豆av| 亚洲狠狠婷婷综合久久图片| 蜜桃久久精品国产亚洲av| 一区二区三区高清视频在线| 狠狠狠狠99中文字幕| 国产成人av激情在线播放| 亚洲真实伦在线观看| 18美女黄网站色大片免费观看| svipshipincom国产片| 国产三级中文精品| 亚洲av熟女| 丁香六月欧美| 岛国视频午夜一区免费看| 真实男女啪啪啪动态图| 国产高清视频在线观看网站| 国产激情偷乱视频一区二区| 国内精品久久久久精免费| 色吧在线观看| 欧美最黄视频在线播放免费| 女生性感内裤真人,穿戴方法视频| 国产精品野战在线观看| 亚洲av电影在线进入| 中文资源天堂在线| 免费观看人在逋| 日本熟妇午夜| 18美女黄网站色大片免费观看| 女同久久另类99精品国产91| 1024手机看黄色片| 好男人电影高清在线观看| 免费在线观看亚洲国产| 美女免费视频网站| 在线播放国产精品三级| 日本精品一区二区三区蜜桃| 成人欧美大片| 中文字幕熟女人妻在线| 国产精品乱码一区二三区的特点| 日韩欧美免费精品| 白带黄色成豆腐渣| 午夜免费激情av| 亚洲 欧美 日韩 在线 免费| 可以在线观看的亚洲视频| 此物有八面人人有两片| 久久草成人影院| www日本黄色视频网| 性欧美人与动物交配| 丁香欧美五月| 久久久久精品国产欧美久久久| 亚洲av美国av| 少妇的逼水好多| 乱人视频在线观看| 久久久久国产精品人妻aⅴ院| 一个人观看的视频www高清免费观看| 在线观看66精品国产| 99riav亚洲国产免费| 三级国产精品欧美在线观看| 在线看三级毛片| 一级a爱片免费观看的视频| 欧美中文综合在线视频| 欧美黄色片欧美黄色片| 一区二区三区国产精品乱码| 51午夜福利影视在线观看| 国产黄片美女视频| 毛片女人毛片| 久久久久亚洲av毛片大全| 狂野欧美激情性xxxx| 久久亚洲精品不卡| 国产色婷婷99| 乱人视频在线观看| 白带黄色成豆腐渣| 夜夜爽天天搞| 激情在线观看视频在线高清| 国产一级毛片七仙女欲春2| 麻豆国产av国片精品| 亚洲国产高清在线一区二区三| 亚洲精品久久国产高清桃花| 国产亚洲精品一区二区www| a级毛片a级免费在线| 97超级碰碰碰精品色视频在线观看| 精品福利观看| 亚洲av熟女| 国语自产精品视频在线第100页| 亚洲av熟女| 欧美成人一区二区免费高清观看| 亚洲va日本ⅴa欧美va伊人久久| 一个人免费在线观看的高清视频| 精品人妻1区二区| 亚洲欧美日韩卡通动漫| 老司机深夜福利视频在线观看| av国产免费在线观看| bbb黄色大片| 国产高清视频在线播放一区| 最后的刺客免费高清国语| 一个人看的www免费观看视频| 亚洲欧美一区二区三区黑人| 少妇的逼水好多| 天堂动漫精品| 尤物成人国产欧美一区二区三区| 日韩 欧美 亚洲 中文字幕| 国产成人欧美在线观看| 午夜福利在线在线| 可以在线观看的亚洲视频| 麻豆久久精品国产亚洲av| 最后的刺客免费高清国语| 国产精品98久久久久久宅男小说| 一夜夜www| 国产成+人综合+亚洲专区| 乱人视频在线观看| 久久精品国产综合久久久| 成人特级av手机在线观看| 国产精品野战在线观看| 哪里可以看免费的av片| 黑人欧美特级aaaaaa片| 午夜a级毛片| 亚洲av电影不卡..在线观看| 亚洲成人中文字幕在线播放| 亚洲精品456在线播放app | 最新在线观看一区二区三区| 久久久久亚洲av毛片大全| 国产精品嫩草影院av在线观看 | 一级毛片女人18水好多| 成年女人看的毛片在线观看| 国产精品女同一区二区软件 | 男女之事视频高清在线观看| a级一级毛片免费在线观看| 午夜视频国产福利| 中文亚洲av片在线观看爽| 久久九九热精品免费| 国产精品1区2区在线观看.| 91麻豆精品激情在线观看国产| 69人妻影院| 亚洲中文日韩欧美视频| a级毛片a级免费在线| 国产午夜精品论理片| 亚洲av第一区精品v没综合| 亚洲av五月六月丁香网| 国产一区二区激情短视频| 男女那种视频在线观看| 亚洲精品美女久久久久99蜜臀| 丁香六月欧美| 长腿黑丝高跟| 真人做人爱边吃奶动态| 精品久久久久久久毛片微露脸| 无限看片的www在线观看| 欧美在线一区亚洲| 日本成人三级电影网站| 十八禁人妻一区二区| 久久久久久人人人人人| 非洲黑人性xxxx精品又粗又长| 国产三级在线视频| 亚洲av电影不卡..在线观看| 一进一出好大好爽视频| 久久草成人影院| 亚洲美女黄片视频| 狂野欧美白嫩少妇大欣赏| 人人妻,人人澡人人爽秒播| 非洲黑人性xxxx精品又粗又长| 婷婷亚洲欧美| 亚洲av熟女| 亚洲欧美日韩东京热| 免费搜索国产男女视频| 免费无遮挡裸体视频| 男人的好看免费观看在线视频| 精品一区二区三区人妻视频| 国产美女午夜福利| 成人三级黄色视频| 欧美国产日韩亚洲一区| 亚洲18禁久久av| 免费一级毛片在线播放高清视频| 久久久久久国产a免费观看| 小蜜桃在线观看免费完整版高清| 国内毛片毛片毛片毛片毛片| 欧美日韩国产亚洲二区| 精品免费久久久久久久清纯| 久久久久国产精品人妻aⅴ院| 久久亚洲真实| 国产视频一区二区在线看| 亚洲五月婷婷丁香| 日本黄大片高清| 麻豆国产av国片精品| 国产视频一区二区在线看| 国产成人影院久久av| 不卡一级毛片| 午夜激情欧美在线| 久久草成人影院| 少妇人妻一区二区三区视频| aaaaa片日本免费| 亚洲国产精品999在线| 精品日产1卡2卡| 黄色女人牲交| 免费观看精品视频网站| 久久久久久久久久黄片| netflix在线观看网站| 啪啪无遮挡十八禁网站| 三级男女做爰猛烈吃奶摸视频| 午夜精品在线福利| 此物有八面人人有两片| 99久久综合精品五月天人人| 免费av毛片视频| 丁香六月欧美| 一夜夜www| 欧美区成人在线视频| 国产麻豆成人av免费视频| 午夜福利18| 欧美日韩亚洲国产一区二区在线观看| 18禁国产床啪视频网站| 脱女人内裤的视频| or卡值多少钱| 中文资源天堂在线| 99热只有精品国产| 少妇的逼水好多| av在线天堂中文字幕| 搞女人的毛片| 成人午夜高清在线视频| 欧美不卡视频在线免费观看| 亚洲七黄色美女视频| 无限看片的www在线观看| 亚洲aⅴ乱码一区二区在线播放| 成人高潮视频无遮挡免费网站| 免费观看的影片在线观看| 精品电影一区二区在线| 很黄的视频免费| 午夜a级毛片| 老师上课跳d突然被开到最大视频 久久午夜综合久久蜜桃 | 观看免费一级毛片| 久久久久久大精品| 久久精品国产综合久久久| 91在线精品国自产拍蜜月 | 嫁个100分男人电影在线观看| 一级黄色大片毛片| 一本一本综合久久| 午夜免费成人在线视频| 日本在线视频免费播放| 在线免费观看的www视频| 午夜视频国产福利| 亚洲七黄色美女视频| 精品国产亚洲在线| 首页视频小说图片口味搜索| 亚洲乱码一区二区免费版| 校园春色视频在线观看| 丰满的人妻完整版| 欧美最黄视频在线播放免费| 亚洲性夜色夜夜综合| av天堂在线播放| 90打野战视频偷拍视频| 老熟妇乱子伦视频在线观看| 国产亚洲精品久久久com| 久久欧美精品欧美久久欧美| 99热这里只有精品一区| 国产91精品成人一区二区三区| 精品久久久久久久人妻蜜臀av| 最近视频中文字幕2019在线8| 婷婷亚洲欧美| 亚洲黑人精品在线| 真实男女啪啪啪动态图|