Spin and valley polarization dependence of resistivity in two dimensions

Takashina, Kei; Niida, Y; Piot, B. A.; Tregurtha, D; Fujiwara, Akira; Hirayama, Y.

doi:10.1103/physrevb.88.201301

Cited by 6 publications

(9 citation statements)

References 30 publications

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“…14 Although many experiments have hinted at ferromagnetic instabilities in these single-band electron gas systems, [15][16][17][18][19][20] unambiguous evidence for magnetism has so far been lacking. Theoretically, order is expected only at extremely low carrier densities, at least in the absence of disorder.…”

Section: -5mentioning

confidence: 99%

Orbital and spin order in oxide two-dimensional electron gases

2017

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We describe a variational theory of multi-band two-dimensional electron gases that captures the interplay between electrostatic confining potentials, orbital-dependent interlayer electronic hopping and electron-electron interactions, and apply it to the d-band two-dimensional electron gases that form near perovskite oxide surfaces and heterojunctions. These multi-band two-dimensional electron gases are prone to the formation of Coulomb-interaction-driven orbitally-ordered nematic groundstates. We find that as the electron density is lowered and interaction effects strengthen, spontaneous orbital order occurs first, followed by spin order. We compare our results with known properties of single-component two-dimensional electron gas systems and comment on closely related physics in semiconductor quantum wells and van der Waals heterostructures.PACS numbers: 73.20.-r,71.15.-m,71.10.-w, 73.21.-b,75.10.-b

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Section: -5mentioning

confidence: 99%

Orbital and spin order in oxide two-dimensional electron gases

2017

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“… 24 . Therefore, in the absence of variation of disorder due to the process of polarizing, one should expect the same increase of resistance due to equivalent reduction of screening, regardless of which degeneracy is lifted 17 .…”

Section: Resultsmentioning

confidence: 99%

“…Thus, by pressing the electrons against the buried-oxide interface (positive δn ), we can increase the valley splitting continuously, and independently control the electron density n . The out-of-plane potential necessarily affects the disorder, however, but the effects of this can be independently examined by applying a negative δn for which there is no valley splitting 17 .…”

Section: Methodsmentioning

confidence: 99%

“…Experimental research into the physical consequences of valley polarizing a two-dimensional electron system in the steady state is led by studies of AlAs and Si-based structures. It has been demonstrated that valley polarization dramatically affects phenomena such as the fractional quantum Hall effect 11 12 13 14 and the metal insulator transition 15 16 17 18 , two effects in which electron–electron interactions are central. Pioneering experiments performed in AlAs indicate that valley polarization also has a strong impact on another effect where electron–electron interactions play crucial roles: spin polarization.…”

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Valley polarization assisted spin polarization in two dimensions

et al. 2015

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Valleytronics is rapidly emerging as an exciting area of basic and applied research. In two-dimensional systems, valley polarization can dramatically modify physical properties through electron–electron interactions as demonstrated by such phenomena as the fractional quantum Hall effect and the metal-insulator transition. Here, we address the electrons' spin alignment in a magnetic field in silicon-on-insulator quantum wells under valley polarization. In stark contrast to expectations from a non-interacting model, we show experimentally that less magnetic field can be required to fully spin polarize a valley-polarized system than a valley-degenerate one. Furthermore, we show that these observations are quantitatively described by parameter-free ab initio quantum Monte Carlo simulations. We interpret the results as a manifestation of the greater stability of the spin- and valley-degenerate system against ferromagnetic instability and Wigner crystalization, which in turn suggests the existence of a new strongly correlated electron liquid at low electron densities.

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“…The relationship between spin polarization and magnetotransport has been actively investigated. [20][21][22] Several groups reported the interplay between spin and orbital effects with an in-plane magnetic field. 23,24 In another research, 25 superconductivity with Rashba spin-orbit interaction and magnetic field was studied for an oxide interface.…”

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Fermi surface distortion induced by interaction between Rashba and Zeeman effects

Choi

Chang

Kim

et al. 2015

Journal of Applied Physics

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To evaluate Fermi surface distortion induced by interaction between Rashba and Zeeman effects, the channel resistance in an InAs quantum well layer is investigated with an in-plane magnetic field transverse to the current direction. In the magnetoresistance curve, the critical point occurs at $3.5 T, which is approximately half of the independently measured Rashba field. To get an insight into the correlation between the critical point in magnetoresistance curve and the Rashba strength, the channel conductivity is calculated using a two-dimensional free-electron model with relaxation time approximation. The critical point obtained from the model calculation is in agreement with the experiment, suggesting that the observation of critical point can be an alternative method to experimentally determine the Rashba parameter. V C 2015 AIP Publishing LLC.Since electronic information can be manipulated by both charge and spin currents, spintronics gives an additional controllability for developing electronic devices. In the field of spintronics, the Rashba spin-orbit interaction is a fascinating phenomenon because it offers a way to manipulate the spin by the external electric field. Fast moving electrons under an electric field feel an effective magnetic field called the Rashba field. The strength of the Rashba effect is expressed as the Rashba parameter a, which is determined by the structural asymmetry or the gate electric field. The gate controlled semiconductor spin device using the Rashba effect has been demonstrated. 1,2 Recently, the Rashba effect in ferromagnet/ heavy metal bilayers has been extensively investigated theoretically 3-12 and experimentally. [13][14][15][16][17][18][19] Especially, the first principles calculation 12 for Co/Pt bilayers showed that an inplane current generates a torque corresponding to the Rashba field indeed. As the two different systems, semiconductor two-dimensional Rashba system and ferromagnet/heavy metal bilayers, share the Rashba effect, a thorough understanding about one system will be also beneficial for understanding basic principles of the other system.The Rashba field as well as the Zeeman field induces the spin splitting in the band structure. Many research groups observed the resistance change as a function of an external magnetic field in a two-dimensional Rashba system. The relationship between spin polarization and magnetotransport has been actively investigated. 20-22 Several groups reported the interplay between spin and orbital effects with an in-plane magnetic field. 23,24 In another research, 25 superconductivity with Rashba spin-orbit interaction and magnetic field was studied for an oxide interface. Their numerical calculation illustrated that two Fermi surfaces (for majority and minority spins) are distorted in the presence of both Rashba spin-orbit interaction and in-plane magnetic field. However, so far coupling of the Rashba and Zeeman splitting effects on Fermi surface distortion has not been clearly reported via a conductivity measurement. Since charge a...

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Spin and valley polarization dependence of resistivity in two dimensions

Cited by 6 publications

References 30 publications

Orbital and spin order in oxide two-dimensional electron gases

Orbital and spin order in oxide two-dimensional electron gases

Valley polarization assisted spin polarization in two dimensions

Fermi surface distortion induced by interaction between Rashba and Zeeman effects

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