Spin relaxation in n-InSb/AlInSb quantum wells

Abstract

Abstract. We have used time resolved spectroscopy to measure the relaxation of spin polarization in InSb/AlInSb quantum wells (QWs) as a function of temperature and mobility. The results are consistent with the D'yakonov-Perel (DP) mechanism for high mobility samples over the temperature range from 50 to 300 K. For low mobility samples at high temperature the Elliott-Yafet and DP mechanisms become comparable. We show that the mobility can in certain circumstances determine which mechanism is dominant, and that above 1 m 2 V −1 s −1 in 20 nm wide InSb QWs it is the DP mechanism. We also give a criterion for the maximum spin lifetime in terms of mobility and temperature, and show that for our 20 nm wide QWs this corresponds to 0.5 ps at 300 K and mobility 1 m 2 V −1 s −1 . Contents

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

“…Optical measurements of the spin dynamics were performed in zero magnetic field using the circularly polarised pump-probe absorption technique described in detail elsewhere [23]. The samples were pumped using 250kHz 1mW laser pulses at 3.4 μm wavelength.…”

Transverse focusing of spin-polarized photocurrents

“…In InSb quantum wells (QWs) the precession frequencies are > 1 THz, which has been demonstrated by the measurement of extremely short spin lifetimes of approximately 0.1 ps in these structures. 3 A downside of this is that the transport of spins becomes the limiting factor. Fortunately, advances in the development of the growth of InSb heterostructures, 4 low temperature electron mobilities of > 100,000 cm 2 V −1 s −1 are now achievable in InAlSb/InSb QWs 5-7 and ballistic transport is evident in devices with greater than µm dimensions, producing spin coherence lengths of 2 µm.…”

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

“…For low-power cw radiation, we used a CH 3 OH laser operating at wavelength λ = 118 μm (frequency f = 2.5 THz) with a power P ≈ 2 mW at the sample position. The radiation was modulated at 120 Hz, allowing the detection of the photoresponse by the standard lock-in technique.…”

“…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.…”