Experimental determination of the Rashba coefficient in InSb/InAlSb quantum wells at zero magnetic field and elevated temperatures

Abstract

Abstract.We report the optical measurement of the spin dynamics at elevated temperatures and in zero magnetic field, for two types of degenerately doped n-InSb quantum wells (QWs), one asymmetric (sample A) and one symmetric (sample B) with regards to the electrostatic potential across the QW. Making use of three directly determined experimental parameters: the spin lifetime, τ s , the sheet carrier concentration, n, and the electron mobility, , we directly extract the zero field spin splitting. For the asymmetric sample where the Rashba interaction is the dominant source of spin splitting, we deduce a room temperature Rashba parameter of  = 0.09 ± 0.1 eVÅ which is in good agreement with calculations and we estimate the Rashba coefficient α 0 (a figure of merit for the ease with which electron spins can be modulated via an electric field). We review the merits/limitations of this approach and the implications of our finding for spintronic devices.

Transverse focusing of spin-polarized photocurrents

“…The smaller value of α = 0.1 eVÅ is closer to the values obtained by experiment and theory. 16,17 The simulated curves T f oc reproduce well the salient features of the experimental data, namely, the focusing peak and the non-monotonic background resistance. These focusing peaks have a FWHM of ∼33 mT, whereas the splitting of the peaks are only 1, 5 and 13 mT, respectively.…”

“…Eq. 4 includes both Zeeman and Rashba terms but excludes Dresselhaus terms for simplicity (as is appropriate for a highly asymmetric InSb QW 16,17 ). The spin S is evolved using the cross product,…”

“…In the InSb devices, the respective energy splittings of 25 and 68 meV are an order of magnitude greater than would be expected. 16,17 In particular the 68 meV splitting is approximately one third of the energy gap of InSb and is therefore unrealistic. Optical orientation of excited carriers allows the possibility to interogate the separate contributions of the spin populations in a ballistic device.…”

Interplay of spin and orbital magnetogyrotropic photogalvanic effects in InSb/(Al,In)Sb quantum well structures

“…A QW of width L W is confined on each side by an InAlSb barrier, with a Te-modulation-doped layer 20 nm above the QW (ME1833 and ME2507 with L W = 20 and 30 nm, respectively). 10,13 The calculated conduction-band profile, electron wave function, and doping position of the 20-nm QW are shown in Fig. 1(a).…”

“…4 This novel material is the subject of numerous experimental studies of transport, optical, magneto-optical, and spin-related phenomena. [1][2][3][4][5][6][7][8][9][10][11][12][13][14] The characteristics driving the interest in this novel narrow gap material are the high carrier mobility, small effective masses, large Landé g * factor, possibility of the mesoscopic spindependent ballistic transport, and a strong spin-orbit coupling. The latter gives rise to a number of optoelectronic effects such as, e.g., terahertz photoconductivity 15 and the circular photogalvanic effect [16][17][18][19][20][21][22] recently observed in InSb QWs.…”