Using a Tunable Quantum Wire To Measure the Large out-of-Plane Spin Splitting of Quasi Two-Dimensional Holes in a GaAs Nanostructure

Srinivasan, Ashwin; Yeoh, L. A.; Klochan, O.; Martin, Theodore P.; Chen, J C H; Micolich, A. P.; Hamilton, A. R.; Reuter, D.; Wieck, A. D.

doi:10.1021/nl303596s

Cited by 21 publications

(31 citation statements)

References 33 publications

(110 reference statements)

Supporting

Mentioning

Contrasting

Order By: Relevance

“…N is the mode number of the plateau under consideration, in this case N = 1. The QPC is characterized by a strong g-factor anisotropy, typical for QPCs embedded in 2DHGs grown along the [001] crystallographic direction [18,19]. The QPC transconductance (numerical derivative with respect to gate voltage) is shown in Fig.…”

Section: Characterization Of the Detector Qpcmentioning

confidence: 99%

Generation and Detection of Spin Currents in Semiconductor Nanostructures with Strong Spin-Orbit Interaction

et al. 2015

View full text Add to dashboard Cite

Storing, transmitting, and manipulating information using the electron spin resides at the heart of spintronics. Fundamental for future spintronics applications is the ability to control spin currents in solid state systems. Among the different platforms proposed so far, semiconductors with strong spin-orbit interaction are especially attractive as they promise fast and scalable spin control with all-electrical protocols. Here we demonstrate both the generation and measurement of pure spin currents in semiconductor nanostructures. Generation is purely electrical and mediated by the spin dynamics in materials with a strong spin-orbit field. Measurement is accomplished using a spin-to-charge conversion technique, based on the magnetic field symmetry of easily measurable electrical quantities. Calibrating the spin-to-charge conversion via the conductance of a quantum point contact, we quantitatively measure the mesoscopic spin Hall effect in a multiterminal GaAs dot. We report spin currents of 174 pA, corresponding to a spin Hall angle of 34%.The generation and detection of spin currents in nanostructures is the central challenge of semiconductor spintronics. On the one hand, spin injection cannot be easily achieved by coupling semiconductors to ferromagnets [1] because of the lack of control over material interfaces [2]. On the other hand, magnetoelectric alternatives exploiting the celebrated spin Hall effect (SHE) [3,4], have delivered only qualitative measurement protocols in transport experiments [5]. Alternatively to all-electrical setups, spin polarizing the current through a quantum point contact (QPC) with a magnetic field allows a quantitative control over spin current generation and detection at the nanoscale [6][7][8]. The latter approach typically requires such high magnetic fields (6 − 8 Tesla) that, as a drawback, the desired magnetoelectric effects are either suppressed or totally altered. This Letter reports two major advances of nanoscale semiconductor spintronics. Namely, we develop novel experimental methods to electrically generate and quantitatively measure spin currents in a two-dimensional semiconductor nanostructure.It is predicted that charge currents flowing through spin-orbit interaction (SOI)-coupled nanostructures are generically accompanied by spin currents, if the spinorbit time is shorter than the electron dwell time [9][10][11][12]. This spin current generation mechanism is purely electrical and based on the mesoscopic SHE (MSHE) [9,10], where the electronic orbital dynamics in chaotic nanostructures cooperates with the SOI to make transport spin dependent. We will consider an open three-terminal quantum dot as represented in Fig. 1(a), where each lead i is a QPC carrying N i spin degenerate modes. Running a charge current I between terminals 1 and 2, a spin current in all terminals, including 3, is expected due to the MSHE.For a weak SOI, the spin currents' amplitude fluctuates from sample to sample with zero average. For cavities with a strong SOI, geometric correlations between ...

show abstract

Section: Characterization Of the Detector Qpcmentioning

confidence: 99%

Generation and Detection of Spin Currents in Semiconductor Nanostructures with Strong Spin-Orbit Interaction

et al. 2015

View full text Add to dashboard Cite

show abstract

“…Experimental research was carried out using optical methods like hot magnetophotoluminescence 57,59-61 , quantum beat spectroscopy 62 , hole burning 63 , spin flip Raman scattering 64 and reflectance difference spectroscopy 65,66 . Also, conductivity measurements in quasi 1D systems were employed to determine the g-factors [67][68][69] of GaAs based 2D hole gases. Hole systems studied over the years include 2D hole gases in both symmetric double heterostructures and inversion layers in single heterojunctions, with differerent dopants and crystallographic orientations.…”

Section: Effective Landé Factormentioning

confidence: 99%

Magnetic field spectral crossings of Luttinger holes in quantum wells

Simion

Lyanda-Geller

2014

Phys. Rev. B

View full text Add to dashboard Cite

We develop an analytic approach to two-dimensional (2D) holes in a magnetic field that allows us to gain insight into physics of measuring the parameters of holes, such as cyclotron resonance, Shubnikov-De Haas effect and spin resonance. We derive hole energies, cyclotron masses and the g-factors in the semiclassical regime analytically, as well as analyze numerical results outside the semiclassical range of parameters, qualitatively explaining experimentally observed magnetic field dependence of the cyclotron mass. In the semiclassical regime with large Landau level indices, and for size quantization energy much bigger than the cyclotron energy, the cyclotron mass coinsides with the in-plane effective mass, calculated in the absence of a magnetic field.The hole g-factor in a magnetic field perpendicular to the 2D plane is defined not only by the constant of direct coupling of the angular momentum of the holes to the magnetic field, but also by the Luttinger constants defining the effective masses of holes. We find that the g-factor for quasi 2D holes with heavy mass in the [001] growth direction in GaAs quantum well is g = 4.05 in the semiclasssical regime. Outside the semiclassical range of parameters, holes behave as a species completely different from electrons. Spectra for size-and magnetic-field-quantized holes are non-equidistant, not fan-like, and exhibit multiple crossings, including crossing in the ground level. We calculate the effect of Dresselhaus terms, which transform some of the crossings into anticrossings, and the effects of the anisotropy of the Luttinger Hamiltonian on the 2D hole spectra. Dresselhaus terms of different symmetries are taken into account, and a regularization procedure is developed for the k 3 z Dresselhaus terms. Control of the non-equidistant levels and crossing structure by the magnetic field can be used to control Landau level mixing in hole systems, and thereby control hole-hole interactions in the magnetic field.

show abstract

“…The spin 3/2 nature of valence band holes in GaAs leads to several unique properties such as a tensor structure of g * with large anisotropy between all three spatial directions [12,13], and tunability of the g-factor across orders of magnitude [14][15][16].…”

mentioning

confidence: 99%

Electrical control of the sign of thegfactor in a GaAs hole quantum point contact

et al. 2016

Self Cite

View full text Add to dashboard Cite

Zeeman splitting of 1D hole subbands is investigated in quantum point contacts (QPCs) fabricated on a (311) oriented GaAs-AlGaAs heterostructure. Transport measurements can determine the magnitude of the g-factor, but cannot usually determine the sign. Here we use a combination of tilted fields and a unique off-diagonal element in the hole g-tensor to directly detect the sign of g * . We are able to tune not only the magnitude, but also the sign of the g-factor by electrical means, which is of interest for spintronics applications. Furthermore, we show theoretically that the resulting behaviour of g * can be explained by the momentum dependence of the spin-orbit interaction.Electrical manipulation of spin is the underlying principal of many proposed spintronic and quantum computing device architectures [1][2][3][4]. In particular, electrical control of the effective Landé g-factor in semiconductor nanostructures has been a major focus of recent research, with theoretical investigations predicting strong g * tunability in both magnitude and sign [5][6][7]. The ability to invert the sign of the g-factor and tune the system through a state of zero spin polarisation (g * = 0) could be a valuable asset in engineering solid-state spin devices [8][9][10].In this regard, quantum confined hole systems in GaAs are prime candidates due to the strong coupling between spin and orbital motion in the valence band [11]. The spin 3/2 nature of valence band holes in GaAs leads to several unique properties such as a tensor structure of g * with large anisotropy between all three spatial directions [12,13], and tunability of the g-factor across orders of magnitude [14][15][16].Previous studies of the g-factor of quantum confined holes revealed a non-monotonic dependance of |g * | on the gate bias, suggestive of a change in sign of g * [6,17]. However, these studies could not directly detect the sign of g * , only its magnitude. In this work, we utilise a novel approach to directly detect the sign of g * by exploiting a unique property of the (311) GaAs hole g-tensor, and demonstrate a gate-controlled sign change of g * in a hole quantum point contact (QPC) on (311) GaAs.We also introduce a theoretical model showing that the observed sign reversal of g * arises from the in-plane momentum dependence of the spin-orbit interaction in the valence band. Typically it is not possible to experimentally probe the directional k-dependence of the 2D hole g-tensor, since transport measurements represent an average over all k-states at the Fermi surface. However, by using an electrostatically controlled QPC fabricated along particular in-plane directions of a 2D hole system, * Alex.Hamilton@unsw.edu.au we can perform a direct spectroscopic measurement of g * , and investigate its dependence on the magnitude and direction of the in-plane momentum [14,17,18].The device used in this work was fabricated from a (311)A-oriented heterostructure, in which a 2D hole system is induced at an AlGaAs/GaAs interface by applying a negative voltage (-0.7V) to a...

show abstract

Using a Tunable Quantum Wire To Measure the Large out-of-Plane Spin Splitting of Quasi Two-Dimensional Holes in a GaAs Nanostructure

Cited by 21 publications

References 33 publications

Generation and Detection of Spin Currents in Semiconductor Nanostructures with Strong Spin-Orbit Interaction

Generation and Detection of Spin Currents in Semiconductor Nanostructures with Strong Spin-Orbit Interaction

Magnetic field spectral crossings of Luttinger holes in quantum wells

Electrical control of the sign of thegfactor in a GaAs hole quantum point contact

Contact Info

Product

Resources

About