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在分子自旋电子学中, 向非磁性的分子器件中注入自旋引起了广泛关注. 在此提出一个新颖的策略, 将磁性引入到与两个扶手椅形石墨烯纳米带电极耦合的单个苯分子器件中, 即将这两个扶手椅形石墨烯纳米带电极的末端切割成锯齿形边缘的三角形石墨烯. 利用第一性原理方法研究了分子结的自旋相关输运性质. 结果表明, 由于锯齿形边缘的三角形石墨烯向扶手椅形石墨烯纳米带电极和苯分子的自旋转移, 导致锯齿形边缘三角形石墨烯的本征磁性减弱. 有趣的是, 虽然锯齿形边缘三角形石墨烯的本征磁性衰减了, 但仍对分子结的自旋输运有显著的贡献. 输运计算表明, 在自旋平行构型下, 可以获得较大的电流自旋极化率. 然而, 在自旋反平行构型下, 电流的自旋极化率发生了反转. 器件隧穿磁电阻的正负可以通过偏压来调控. 这项工作提出了一个在新型分子自旋电子器件中设计和应用石墨烯纳米带的有趣方法.
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关键词:
- 分子自旋电子学 /
- 自旋输运 /
- 单分子结 /
- 锯齿形边缘三角形石墨烯
Injecting spins into nonmagnetic molecular devices has attracted much attention in molecular spintronics. Herein, we propose a novel strategy to introduce magnetism into a single benzene molecule coupled with two armchair graphene nanoribbons (AGNR) electrodes, where the ends of two AGNR electrodes are cut into zigzag-edge triangular graphenes (ZTGs). The spin-dependent transport properties of the molecular junction are investigated by using the density functional theory (DFT) combined with the non-equilibrium Green’s function (NEGF) method. The analyses of the spin-dependent projected density of states and the net spin density distribution of the scattering region reveal that the intrinsic magnetism of the ZTGs is weakened, owing to spin transfer from ZTGs to AGNR electrodes and the benzene molecule. More interestingly, the attenuated intrinsic magnetism of the ZTGs can still contribute to a significant spin transport of the molecular junction. Transport calculations show that in the parallel spin configuration, a large spin polarization of nearly 90% current is obtained. However, the spin polarization of current is reversed in antiparallel spin configuration. Positive or negative tunneling magnetoresistance (TMR) can be modulated by bias voltage. A TMR up to 53% is obtained in the device. The results are further analyzed from the transmission spectra and local density of states. This work presents a promising potential applications of the ZTGs in the field of molecular spintronics, which can contribute to the design of graphene nanoribbons based molecular spintronic devices.-
Keywords:
- molecular spintronics /
- spin transport /
- single-molecule junctions /
- zigzag-edge triangular graphene
[1] 李婧, 丁帅帅, 胡文平 2022 物理学报 71 067201Google Scholar
Li J, Ding S S, Hu W P 2022 Acta Phys. Sin. 71 067201Google Scholar
[2] 蒋小红, 秦泗晨, 幸子越, 邹星宇, 邓一帆, 王伟, 王琳 2021 物理学报 70 127801Google Scholar
Jiang X H, Qin S C, Xing Z Y, Zou X Y, Deng Y F, Wang W, Wang L 2021 Acta Phys. Sin. 70 127801Google Scholar
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[5] Xiang D, Wang X L, Jia C C, Lee T, Guo X F 2016 Chem. Rev. 116 4318Google Scholar
[6] Novoselov K S, Geim A K, Morozov S V, Jiang D, Zhang Y, Dubonos S V, Grigorieva I V, Firsov A A 2004 Science 306 666Google Scholar
[7] Geim A K, Novoselov K S 2007 Nat. Mater. 6 183Google Scholar
[8] Tang G P, Zhou J C, Zhang Z H, Deng X Q, Fan Z Q 2013 Carbon 60 94Google Scholar
[9] Hüser F, Solomon G C 2015 J. Chem. Phys. 143 214302Google Scholar
[10] Jia C C, Ma B J, Xin N, Guo X F 2015 Acc. Chem. Res. 48 2565Google Scholar
[11] Li Q, Duchemin I, Xiong S Y, Solomon G C, Donadio D 2015 J. Phys. Chem. C 119 24636Google Scholar
[12] Neto A H C, Guinea F, Peres N M R, Novoselov K S, Geim A K 2009 Rev. Mod. Phys. 81 109Google Scholar
[13] Zhang Y, Tan Y W, Stormer H L, Kim P 2005 Nature 438 201Google Scholar
[14] Deng X Q, Zhang Z H, Tang G P, Fan Z Q, Yang C H 2014 Carbon 66 646Google Scholar
[15] Zeng J, Chen K Q, He J, Zhang X J, Sun C Q 2011 J. Phys. Chem. C 115 25072Google Scholar
[16] Goto H, Uesugi E, Eguchi R, Fujiwara A, Kubozono Y 2013 Nano Lett. 13 1126Google Scholar
[17] Owens F J 2008 J. Chem. Phys. 128 194701Google Scholar
[18] Ezawa M 2008 Physica E 40 1421Google Scholar
[19] Ezawa M 2007 Phys. Rev. B 76 245415Google Scholar
[20] Berger C, Song Z, Li X, Wu X, Brown N, Naud C, Mayou D, Li T, Hass J, Marchenkov A N, Conrad E H, First P N, de Heer W A 2006 Science 312 1191Google Scholar
[21] Räder H J, Rouhanipour A, Talarico A M, Palermo V, Samorì P, Müllen K 2006 Nat. Mater. 5 276Google Scholar
[22] Saffarzadeh A, Farghadan R 2011 Appl. Phys. Lett. 98 023106Google Scholar
[23] Zou D Q, Cui B, Kong X R, Zhao W K, Zhao J F, Liu D S 2015 Phys. Chem. Chem. Phys. 17 11292Google Scholar
[24] Fan Z Q, Xie F, Jiang X W, Wei Z M, Li S S 2016 Carbon 110 200Google Scholar
[25] Sanvito S 2010 Nat. Phys. 6 562Google Scholar
[26] 崔兴倩, 刘乾, 范志强, 张振华 2020 物理学报 69 248501Google Scholar
Cui X Q, Liu Q, Fan Z Q, Zhang Z H 2020 Acta Phys. Sin. 69 248501Google Scholar
[27] Yao Y X, Wang C Z, Zhang G P, Ji M, Ho K M 2009 J. Phys. Condens. Matter 21 235501Google Scholar
[28] Zhang G P, Fang X W, Yao Y X, Wang C Z, Ding Z J, Ho K M 2010 J. Phys. Condens. Matter 23 025302Google Scholar
[29] Candini A, Klyatskaya S, Ruben M, Wernsdorfer W, Affronte M 2011 Nano Lett. 11 2634Google Scholar
[30] Son Y W, Cohen M L, Louie S G 2006 Nature 444 347Google Scholar
[31] Son Y W, Cohen M L, Louie S G 2006 Phys. Rev. Lett. 97 216803Google Scholar
[32] Kan E, Li Z, Yang J, Hou J G 2008 J. Am. Chem. Soc. 130 4224Google Scholar
[33] Zhang J J, Zhang Z H, Tang G P, Deng X Q, Fan Z Q 2014 Org. Electron. 15 1338Google Scholar
[34] Tang G P, Zhou J C, Zhang Z H, Deng X Q, Fan Z Q 2012 Appl. Phys. Lett. 101 023104Google Scholar
[35] Ling Y C, Ning F, Zhou Y H, Chen K Q 2015 Org. Electron. 19 92Google Scholar
[36] Sawada K, Ishii F, Saito M 2010 Phys. Rev. B 82 245426Google Scholar
[37] Inoue J, Fukui K, Kubo T, Nakazawa S, Sato K, Shiomi D, Morita Y, Yamamoto K, Takui T, Nakasuji K 2001 J. Am. Chem. Soc. 123 12702Google Scholar
[38] Ci L, Xu Z, Wang L, Gao W, Feng D, Kelly K F, Yakobson B I, Ajayan P M 2008 Nano Res. 1 116Google Scholar
[39] Chuvilin A, Meyer J C, Algara-Siller G, Kaiser U 2009 New J. Phys. 11 083019Google Scholar
[40] Brandbyge M, Mozos J L, Ordejón P, Taylor J, Stokbro K 2002 Phys. Rev. B 65 165401Google Scholar
[41] José M S, Emilio A, Julian D G, Alberto G, Javier J, Pablo O, Daniel S P 2002 J. Phys. Condens. Matter 14 2745Google Scholar
[42] Smidstrup S, Markussen T, Vancraeyveld P, et al. 2020 J. Phys. Condens. Matter 32 015901Google Scholar
[43] Landauer R 1970 Philos. Mag. 21 863Google Scholar
[44] Xiong Z H, Wu D, Vardeny Z V, Shi J 2004 Nature 427 821Google Scholar
[45] He G M, Qiu S, Cui Y J, Yu C J, Miao Y Y, Zhang G P, Ren J F, Wang C K, Hu G C 2019 J. Mater. Sci. 54 5551Google Scholar
[46] Qiu S, Miao Y Y, Zhang G P, Ren J F, Wang C K, Hu G C 2019 J. Magn. Magn. Mater. 479 247Google Scholar
[47] Solomon G C, Herrmann C, Hansen T, Mujica V, Ratner M A 2010 Nat. Chem. 2 223Google Scholar
[48] Szulczewski G 2012 Top. Curr. Chem. 312 275Google Scholar
[49] Liu Q, Li J J, Wu D, Deng X Q, Zhang Z H, Fan Z Q, Chen K Q 2021 Phys. Rev. B 104 045412Google Scholar
[50] Zeng Y J, Wu D, Cao X H, Zhou W X, Tang L M, Chen K Q 2020 Adv. Funct. Mater. 30 1903873Google Scholar
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图 1 分子结模型示意图. 分子结由中心苯分子和两个AGNRs电极组成, AGNRs电极与分子相邻的末端被切割成ZTGs. 红色和蓝色区域可以设置为P和AP自旋构型
Fig. 1. Schematic of investigated molecular junction consisting of a benzene molecule sandwiched between two AGNRs electrodes. The ends of the AGNRs electrodes adjacent to the benzene molecule are cutting into ZTGs. The red and blue areas can be set to P or AP spin configuration.
图 3 零偏压下, P (a)和AP (b)自旋构型的净自旋密度分布. 洋红色和青色分别表示自旋向上和自旋向下的密度分布. 图中阈值设为0.02
Fig. 3. The net spin density distribution for the P (a) and AP (b) spin configurations under zero bias voltage. Magenta and cyan colors represent the spin-up and spin-down density distribution, respectively. The isovalue is 0.02.
图 6 (a), (b) 2.0 V和3.0 V时P构型分子结的自旋相关透射谱; (c), (d) 2.0 V和3.0 V时AP构型分子结的自旋相关透射谱; (e), (f) 2.0 V和3.0 V时P和AP自旋构型分子结的总透射谱. 图中虚线均表示偏压窗
Fig. 6. (a), (b) Spin-dependent transmission spectra of molecular junction in P spin configuration at 2.0 and 3.0 V, respectively; (c), (d) spin-dependent transmission spectra of molecular junction in AP spin configuration at 2.0 and 3.0 V; (e), (f) total transmission spectra of molecular junction in P and AP spin configurations at 2.0 and 3.0 V, respectively. The dashed lines indicate the bias window.
图 7 2.0 V时P构型下, 电子的LDOS分布 (a) 能量在0.3 eV处自旋向上的电子; (b) 能量在–0.167 eV处自旋向下的电子. 3.0 V时P构型下–0.6 eV能量处电子的LDOS分布 (c)自旋向上的电子; (d)自旋向下的电子. 图中阈值均为0.02
Fig. 7. LDOS of electrons in P spin configuration under 2.0 V: (a) Spin-up electrons at the energy of 0.3 eV; (b) spin-down electrons at the energy of –0.167 eV. LDOS of electrons at the energy of –0.6 eV in P spin configuration under 3.0 V: (c) Spin-up electrons; (d) spin-down electrons. The isovalue is 0.02.
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[1] 李婧, 丁帅帅, 胡文平 2022 物理学报 71 067201Google Scholar
Li J, Ding S S, Hu W P 2022 Acta Phys. Sin. 71 067201Google Scholar
[2] 蒋小红, 秦泗晨, 幸子越, 邹星宇, 邓一帆, 王伟, 王琳 2021 物理学报 70 127801Google Scholar
Jiang X H, Qin S C, Xing Z Y, Zou X Y, Deng Y F, Wang W, Wang L 2021 Acta Phys. Sin. 70 127801Google Scholar
[3] Jia C C, Guo X F 2013 Chem. Soc. Rev. 42 5642Google Scholar
[4] Metzger R M 2015 Chem. Rev. 115 5056Google Scholar
[5] Xiang D, Wang X L, Jia C C, Lee T, Guo X F 2016 Chem. Rev. 116 4318Google Scholar
[6] Novoselov K S, Geim A K, Morozov S V, Jiang D, Zhang Y, Dubonos S V, Grigorieva I V, Firsov A A 2004 Science 306 666Google Scholar
[7] Geim A K, Novoselov K S 2007 Nat. Mater. 6 183Google Scholar
[8] Tang G P, Zhou J C, Zhang Z H, Deng X Q, Fan Z Q 2013 Carbon 60 94Google Scholar
[9] Hüser F, Solomon G C 2015 J. Chem. Phys. 143 214302Google Scholar
[10] Jia C C, Ma B J, Xin N, Guo X F 2015 Acc. Chem. Res. 48 2565Google Scholar
[11] Li Q, Duchemin I, Xiong S Y, Solomon G C, Donadio D 2015 J. Phys. Chem. C 119 24636Google Scholar
[12] Neto A H C, Guinea F, Peres N M R, Novoselov K S, Geim A K 2009 Rev. Mod. Phys. 81 109Google Scholar
[13] Zhang Y, Tan Y W, Stormer H L, Kim P 2005 Nature 438 201Google Scholar
[14] Deng X Q, Zhang Z H, Tang G P, Fan Z Q, Yang C H 2014 Carbon 66 646Google Scholar
[15] Zeng J, Chen K Q, He J, Zhang X J, Sun C Q 2011 J. Phys. Chem. C 115 25072Google Scholar
[16] Goto H, Uesugi E, Eguchi R, Fujiwara A, Kubozono Y 2013 Nano Lett. 13 1126Google Scholar
[17] Owens F J 2008 J. Chem. Phys. 128 194701Google Scholar
[18] Ezawa M 2008 Physica E 40 1421Google Scholar
[19] Ezawa M 2007 Phys. Rev. B 76 245415Google Scholar
[20] Berger C, Song Z, Li X, Wu X, Brown N, Naud C, Mayou D, Li T, Hass J, Marchenkov A N, Conrad E H, First P N, de Heer W A 2006 Science 312 1191Google Scholar
[21] Räder H J, Rouhanipour A, Talarico A M, Palermo V, Samorì P, Müllen K 2006 Nat. Mater. 5 276Google Scholar
[22] Saffarzadeh A, Farghadan R 2011 Appl. Phys. Lett. 98 023106Google Scholar
[23] Zou D Q, Cui B, Kong X R, Zhao W K, Zhao J F, Liu D S 2015 Phys. Chem. Chem. Phys. 17 11292Google Scholar
[24] Fan Z Q, Xie F, Jiang X W, Wei Z M, Li S S 2016 Carbon 110 200Google Scholar
[25] Sanvito S 2010 Nat. Phys. 6 562Google Scholar
[26] 崔兴倩, 刘乾, 范志强, 张振华 2020 物理学报 69 248501Google Scholar
Cui X Q, Liu Q, Fan Z Q, Zhang Z H 2020 Acta Phys. Sin. 69 248501Google Scholar
[27] Yao Y X, Wang C Z, Zhang G P, Ji M, Ho K M 2009 J. Phys. Condens. Matter 21 235501Google Scholar
[28] Zhang G P, Fang X W, Yao Y X, Wang C Z, Ding Z J, Ho K M 2010 J. Phys. Condens. Matter 23 025302Google Scholar
[29] Candini A, Klyatskaya S, Ruben M, Wernsdorfer W, Affronte M 2011 Nano Lett. 11 2634Google Scholar
[30] Son Y W, Cohen M L, Louie S G 2006 Nature 444 347Google Scholar
[31] Son Y W, Cohen M L, Louie S G 2006 Phys. Rev. Lett. 97 216803Google Scholar
[32] Kan E, Li Z, Yang J, Hou J G 2008 J. Am. Chem. Soc. 130 4224Google Scholar
[33] Zhang J J, Zhang Z H, Tang G P, Deng X Q, Fan Z Q 2014 Org. Electron. 15 1338Google Scholar
[34] Tang G P, Zhou J C, Zhang Z H, Deng X Q, Fan Z Q 2012 Appl. Phys. Lett. 101 023104Google Scholar
[35] Ling Y C, Ning F, Zhou Y H, Chen K Q 2015 Org. Electron. 19 92Google Scholar
[36] Sawada K, Ishii F, Saito M 2010 Phys. Rev. B 82 245426Google Scholar
[37] Inoue J, Fukui K, Kubo T, Nakazawa S, Sato K, Shiomi D, Morita Y, Yamamoto K, Takui T, Nakasuji K 2001 J. Am. Chem. Soc. 123 12702Google Scholar
[38] Ci L, Xu Z, Wang L, Gao W, Feng D, Kelly K F, Yakobson B I, Ajayan P M 2008 Nano Res. 1 116Google Scholar
[39] Chuvilin A, Meyer J C, Algara-Siller G, Kaiser U 2009 New J. Phys. 11 083019Google Scholar
[40] Brandbyge M, Mozos J L, Ordejón P, Taylor J, Stokbro K 2002 Phys. Rev. B 65 165401Google Scholar
[41] José M S, Emilio A, Julian D G, Alberto G, Javier J, Pablo O, Daniel S P 2002 J. Phys. Condens. Matter 14 2745Google Scholar
[42] Smidstrup S, Markussen T, Vancraeyveld P, et al. 2020 J. Phys. Condens. Matter 32 015901Google Scholar
[43] Landauer R 1970 Philos. Mag. 21 863Google Scholar
[44] Xiong Z H, Wu D, Vardeny Z V, Shi J 2004 Nature 427 821Google Scholar
[45] He G M, Qiu S, Cui Y J, Yu C J, Miao Y Y, Zhang G P, Ren J F, Wang C K, Hu G C 2019 J. Mater. Sci. 54 5551Google Scholar
[46] Qiu S, Miao Y Y, Zhang G P, Ren J F, Wang C K, Hu G C 2019 J. Magn. Magn. Mater. 479 247Google Scholar
[47] Solomon G C, Herrmann C, Hansen T, Mujica V, Ratner M A 2010 Nat. Chem. 2 223Google Scholar
[48] Szulczewski G 2012 Top. Curr. Chem. 312 275Google Scholar
[49] Liu Q, Li J J, Wu D, Deng X Q, Zhang Z H, Fan Z Q, Chen K Q 2021 Phys. Rev. B 104 045412Google Scholar
[50] Zeng Y J, Wu D, Cao X H, Zhou W X, Tang L M, Chen K Q 2020 Adv. Funct. Mater. 30 1903873Google Scholar
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