Semiclassical theory of anisotropic transport at 
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 interfaces under an in-plane magnetic field

Bovenzi, N.; Diez, M.

doi:10.1103/physrevb.95.205430

Cited by 17 publications

(20 citation statements)

References 57 publications

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“…For small SOC, this interband scattering gets suppressed by an in-plane magnetic field leading to large negative magnetoresistance. Changing the angle of the in-plane magnetic field, we find strong angledependent current damping and a large AMR, with many angular harmonics at higher fields, as observed experimentally 30 and in previous theoretical work 23,57 .…”

Section: Introductionsupporting

confidence: 87%

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Anisotropic magnetoresistance in multiband systems: Two-dimensional electron gases and polar metals at oxide interfaces

2019

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Low density two-dimensional electron gases (2DEGs) with spin-orbit coupling are highly sensitive to an in-plane magnetic field, which impacts their Fermi surfaces and transport properties. Such 2DEGs, formed at transition metal oxide surfaces or interfaces, can also undergo surface phase transitions leading to polar metals that exhibit electronic nematicity. Motivated by experiments on such systems, we theoretically study magnetotransport in t2g orbital systems, using Hamiltonians that include atomic spin-orbit coupling and broken inversion symmetry, for both square symmetry (001) and hexagonal symmetry (111) 2DEGs. Using a numerical solution to the full multiband matrix-Boltzmann equation, together with insights gleaned from the impurity scattering overlap matrix, we explore the anisotropic magnetoresistance (AMR) in the presence of impurities which favor small momentum scattering. We find that transport in the (001) 2DEG is dominated by a single pair of bands, weakly coupled by impurity scattering, one of which has a larger Fermi velocity while the other provides an efficient current-relaxation mechanism. This leads to strong angle-dependent current damping and a large AMR with many angular harmonics. In contrast, AMR in the (111) 2DEG typically features a single cos(2ϑ) harmonic, with the angle-averaged magnetoresistance being highly tunable by a symmetry-allowed trigonal distortion. We also explore how the (111) 2DEG Fermi sufaces are impacted by electronic nematicity via a surface phase transition into a 2D polar metal for which we discuss a Landau theory, and we show that this leads to distinct symmetry components and higher angular harmonics in the AMR. Our results are in qualitative agreement with experiments from various groups for 2DEGs at the SrTiO3 surface and the LaAlO3-SrTiO3 interface.

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Section: Introductionsupporting

confidence: 87%

“…Our results also suggest that the AMR harmonics do not directly reflect the underlying lattice rotational symmetries of the FS. For the (001) 2DEG, our work builds upon previous important numerical studies 23,57 . Here, we further suggest simple physical mechanisms for the observations.…”

Section: Introductionmentioning

confidence: 93%

Anisotropic magnetoresistance in multiband systems: Two-dimensional electron gases and polar metals at oxide interfaces

2019

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“…In combination with the Rashba SOC this produces a spin splitting at the avoided level crossing that is much larger than the one present at the zone centre. An effective tight-binding hamiltonian modelling this electronic structure and its spin texture was proposed by Diez et al [41,42] In this picture, the Rashba SOC component due to the breaking of inversion symmetry adds on top of this effect but is small. This new scenario questions the coupling of the spin to the momentum.…”

Section: Srtiomentioning

confidence: 99%

A spin–orbit playground: surfaces and interfaces of transition metal oxides

et al. 2018

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Within the last twenty years, the status of the spin-orbit interaction has evolved from that of a simple atomic contribution to a key effect that modifies the electronic band structure of materials. It is regarded as one of the basic ingredients for spintronics, locking together charge and spin degrees of freedom and recently it is instrumental in promoting a new class of compounds, the topological insulators. In this review, we present the current status of the research on the spin-orbit coupling in transition metal oxides, discussing the case of two semiconducting compounds, [Formula: see text] and [Formula: see text], and the properties of surface and interfaces based on these. We conclude with the investigation of topological effects predicted to occur in different complex oxides.

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“…The dependence of C 6 on V g suggests that the higher electronic band couples strongly with the crystal sites. It would be natural to presume that the band with higher J creates stronger AMR response.Recent theoretical studies on the (100) interface have shown a strong influence of spin-orbit interactions on crystalline AMR effects [23,35,42]. Fête et al have suggested that the AMR amplitude should be proportional to the square of ∆ SO /E F , where ∆ SO and E F are the Rasba spin-orbit coupling strength and the Fermi energy, respectively [23,43].…”

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confidence: 99%

Six-fold crystalline anisotropic magnetoresistance in the (111) LaAlO3/SrTiO3 oxide interface

et al. 2017

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We measured the magnetoresistance of the 2D electron liquid formed at the (111) LaAlO3/SrTiO3 interface. The hexagonal symmetry of the interface is manifested in a six-fold crystalline component appearing in the anisotropic magnetoresistance (AMR) and planar Hall data, which agree well with symmetry analysis we performed. The six-fold component increases with carrier concentration, reaching 15% of the total AMR signal. Our results suggest the coupling between higher itinerant electronic bands and the crystal as the origin of this effect and demonstrate that the (111) oxide interface is a unique hexagonal system with tunable magnetocrystalline effects.Introduction.-The two dimensional electron liquid formed at the (100) interface between the two nonmagnetic insulators LaAlO 3 (LAO) and SrTiO 3 (STO) [1] features numerous properties, such as superconductivity [2,3] and spin-orbit coupling [4,5], which are tunable by a gate voltage. Past studies have shown evidence for magnetic order (possibly co-existing with superconductivity) whose exact character is not yet clear [6][7][8][9][10][11][12][13][14][15], prompting much theoretical activity [16][17][18][19].In-plane anisotropic magnetoresistance (AMR) can be employed as a probe for the magnetic properties of 2D structures, since it is sensitive to spin texture and spin-orbit interaction [20]. In the absence of crystalline anisotropy, rotating the magnetic field in the 2D plane results in a standard two-fold symmetric AMR term that depends on the angle between the magnetic field and the current. Such dependence has been observed in (100) LAO/STO [21][22][23]. It is absent in nonpolar doped STO heterostructure [22] and can hence be related to the Rashba spin-orbit interaction which is expected to be less important in the latter. It has been suggested that an easy axis for magnetization can be observed in the AMR [18], however, the almost square symmetry of the interfacial crystal structure makes it difficult to distinguish between the two-fold term and the crystalline one. Here we explored a different interface, which has a hexagonal in-plane symmetry, namely the (111) LAO/STO heterostructure.The stacking of (111) perovskite ABO 3 layers is AO 3 /B/AO 3 /B [ Fig. 1(a)], and therefore with alternating -3e and +3e charges in LaAlO 3 , whereas -4e and +4e in SrTiO 3 [24]. In addition to the different polar structure compared to the (100) interface, its hexagonal symmetry has been predicted to be a key ingredient for the realization of various nontrivial states [25,26]. Recently, six-fold Fermi contour related to the symmetry of STO (111) surface has been observed by angle resolved photoemission [27,28]. However, a distinct signature of six-fold symmetry of the (111) LAO/STO interface is lacking. In this Rapid Communication we show theoretically and ex- * yodagan@post.tau.ac.il perimentally that a six-fold crystalline cos(6θ) term can be observed in the AMR of the (111) LAO/STO interface. This term depends on carrier concentration, suggesting that coupling between the lat...

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Semiclassical theory of anisotropic transport at LaAlO3/SrTiO3 interfaces under an in-plane magnetic field

Cited by 17 publications

References 57 publications

Anisotropic magnetoresistance in multiband systems: Two-dimensional electron gases and polar metals at oxide interfaces

Anisotropic magnetoresistance in multiband systems: Two-dimensional electron gases and polar metals at oxide interfaces

A spin–orbit playground: surfaces and interfaces of transition metal oxides

Six-fold crystalline anisotropic magnetoresistance in the (111) LaAlO3/SrTiO3 oxide interface

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