铁磁-量子点-超导体异质结中的自旋电导(英文)
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摘要
分析铁磁-量子点-超导体异质结中,量子点内存在自旋翻转相互作用时的自旋输运问题.采用非平衡格林函数方法,计算隧穿自旋流和自旋电导.结果表明,即使在一般温度和自旋极化强度下,自旋电导依赖于铁磁体内交换场方向,产生可控的巨自旋磁阻效应.
We analyze the spin transport in a ferromagnet/quantum dot/superconductor junction by assuming spin-flip interaction on the quantum dot. The nonequilibrium Green's function method is employed to calculate the tunneling spin current and spin conductance. It is shown that the spin conductance depends sensitively on the orientation of exchange field in the ferromagnet,leading to a controllable giant spin tunneling magnetoresistance effect,even in the moderate temperature and spin polarization regime.
We analyze the spin transport in a ferromagnet/quantum dot/superconductor junction by assuming spin-flip interaction on the quantum dot. The nonequilibrium Green's function method is employed to calculate the tunneling spin current and spin conductance. It is shown that the spin conductance depends sensitively on the orientation of exchange field in the ferromagnet,leading to a controllable giant spin tunneling magnetoresistance effect,even in the moderate temperature and spin polarization regime.
引文
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[2]Zuti'c I,Fabian J,Sarma S D.Spintronics:fundamentals and applications[J].Rev Mod Phys,2004,76:323-410.
[3]Golubov A A,Kupriyanov M Y,Ll'i chev E.The currentphase relation in Josephson junctions[J].Rev Mod Phys,2004,76:411-469.
[4]Buzdin A I.Proximity effects in superconductor-ferromagnet heterostructures[J].Rev Mod Phys,2005,77:935-976.
[5]Bergeret F S,Volkov A F,Efetov K B.Odd triplet superconductivity and related phenomena in superconductorferromagnet structures[J].Rev Mod Phys,2005,77:1321-1373.
[6]Zhu Y,Sun Q F,Lin T H.Andreev reflection through a quantum dot coupled with two ferromagnets and a superconductor[J].Phys Rev B,2001,65:024 516.
[7]Feng J F,Xiong S J.Tunneling resonances and Andreev reflection in transport of electrons through a ferromagnetic metal/quantum dot/superconductor system[J].Phys Rev B,2003,67:045 316.
[8]Cao X F,Shi Y M,Song X L,et al.Spin-dependent Andreev reflection tunneling through a quantum dot with intradot spin-flip scattering[J].Phys Rev B,2004,70:235341.
[9]Zhu Y,Lin T H,Sun Q F.Writing spin in a quantum dot with ferromagnetic and superconducting electrodes[J].Phys Rev B,2004,69:121 302(R).
[10]Domański T,Donabidowicz A.Interplay between particle-hole splitting and the Kondo effect in quantum dots[J].Phys Rev B,2008,78:073 105.
[11]Liu Y S,Fan X H,Xia Y J.Andreev reflection in a quantum dot coupled to ferromagnetic and superconductor leads under magnetic fields[J].Phys Lett A,2008,372:1930-1936.
[12]Song H Y,Zhou S P.Intradot spin-flip Andreev reflection tunneling through a ferromagnet-quantum dot-superconductor system with ac field[J].Phys Lett A,2008,372:6773-6777.
[13]Pan H,LüR.Spin accumulation in coupled quantum dots with ferromagnetic and superconducting electrodes[J].Physica B,2008,403:3125-3129.
[14]Hofstetter L,Geresdi A,Aagesen M,et al.Ferromagnetic proximity effect in a ferromagnet-quantum-dot-superconductor device[J].Phys Rev Lett,2010,104:246 804.
[15]Ning W T,Chen C J,Cheng Q,et al.Tunneling magnetoresistance effect in ferromagnet/quantum dot/superconductor junctions[J].Physica C,2013,487:42-46.
[16]Rudziński W,Barna's J.Tunnel magnetoresistance in ferromagnetic junctions:Tunneling through a single discrete level[J].Phys Rev B,2001,64:085 318.
[17]Zhang P,Xue Q K,Wang Y P,et al.Spin-dependent transport through an interacting quantum dot[J].Phys Rev Lett,2002,89:286 803.
[18]Sergueev N,Sun Q F,Guo H,et al.Spin-polarized transport through a quantum dot:Anderson model with on-site Coulomb repulsion[J].Phys Rev B,2002,65:165 303.
[19]Lui C K,Wang B G,Wang J.Ac transport through a resonant level between ferromagnetic electrodes[J].Phys Rev B,2004,70:205 316.
[20]Rudziński W,Barna's J,Wilczyński M.Magnetically controlled impurities in quantum wires with strong Rashba coupling[J].Phys Rev B,2005,71:085 318.
[21]Zhou Y Q,Wang R Q,Wang B G,et al.Angle-dependent tunneling through quantum dots coupled to noncollinearly oriented magnetic leads and subject to magnetic fields[J].Phys Rev B,2007,76:075 343.
[22]Ma M J,Jalil M B A,Tan S G.Spin polarized transport in an asymmetric ferromagnetic/quantum dot/ferromagnetic system[J].J Appl Phys,2009,105:07C 912.
[23]Deutscher G.Andreev-saint-james reflections:A probe of cuprate superconductors[J].Rev Mod Phys,2005,77:109-135.
[24]Wingreen N S,Jauho A P,Meir Y.Time-dependent transport through a mesoscopic structure[J].Phys Rev B,1993,48:8487-8490.
[25]Cuevas J C,Martin-Rodero A,Yeyati A L.Hamiltonian approach to the transport properties of superconducting quantum point contacts[J].Phys Rev B,1996,54:7366-7379.
[26]Sun Q F,Wang J,Lin T H.Control of the supercurrent in a mesoscopic four-terminal Josephson junction[J].Phys Rev B,2000,62:648-660.
[27]Zeng Z Y,Li B W,Claro F.Electronic transport in hybrid mesoscopic structures:A nonequilibrium green function approach[J].Phys Rev B,2003,68:115 319.
[28]Meir Y,Wingreen N S.Landauer formula for the current through an interacting electron region[J].Phys Rev Lett,1992,68:2512-2515.
[29]Jauho A P,Wingreen N S,Meir Y.Time-dependent transport in interacting and noninteracting resonant-tunneling systems[J].Phys Rev B,1994,50:5528-5544.
[30]Sun Q F,Wang J,Lin T H.Photon-assisted Andreev tunneling through a mesoscopic hybrid system[J].Phys Rev B,1999,59:13 126-13 138.