Exchange biasing of the ferromagnetic semiconductor Ga1−xMnxAs

Abstract

We demonstrate the exchange coupling of a ferromagnetic semiconductor (Ga 1-x Mn x As) with an overgrown antiferromagnet (MnO). Unlike most conventional exchange biased systems, the blocking temperature of the antiferromagnet (T B = 48 ± 2 K) and the Curie temperature of the ferromagnet (T C = 55.1 ± 0.2 K) are comparable. The resulting exchange bias manifests itself as a clear shift in the magnetization hysteresis loop when the bilayer is cooled in the presence of an applied magnetic field and an enhancement of the coercive field. * nsamarth@phys.psu.edu

Asymmetric Magnetization Reversal in the Exchange-Biased MnO/(Ga,Mn)As Heterostructure Studied by Ferromagnetic Resonance

“…SQUID magnetometry revealed significant shift of the hysteresis loop, H EB ≈ 200 Oe, with no reduction of H EB in a series of measurements carried out in succession (no training effect) [7,8]. Similar absence of training effect was observed for the exchange-induced unidirectional anisotropy of FM (i.e., the breaking of the 180…”

“…Recently, the successful attempt of exchange biasing of ferromagnetic (Ga,Mn)As (T C ≈ 55 ÷ 70 K) with antiferromagnetic MnO (T N ≈ 120 K) was reported [7]. SQUID magnetometry revealed significant shift of the hysteresis loop, H EB ≈ 200 Oe, with no reduction of H EB in a series of measurements carried out in succession (no training effect) [7,8].…”

Phase separation and exchange biasing in the ferromagnetic IV-VI semiconductor Ge1−xMnxTe

“…The observed lateral exchange biasing is well known for coupled FM and AFM layer systems 11 and has been observed, e.g., for bilayers of FM GaMnAs coupled to AFM MnO. 12 Thus, there is strong evidence for the presence of an AFM phase within this sample. The coexistence of a vertical and a lateral shift in the hysteresis loops is an indication for additional uncompensated spins pinned during FC in layered FM/AFM structures 13 or in phase-separated FM systems.…”

Electrical characterisation of (Ga,Mn,Cr)As thin films grown by molecular beam epitaxy

“…The majority of work has focused on (Ga,Mn)As, and has led to significant improvements in material quality as well as new device paradigms: the highest ferromagnetic transition temperatures are now in excess of 150 K [1][2][3]; the key features of spintronics including tunnelling magnetoresistance [4], exchange bias [5] and efficient spin injection [6] have been demonstrated in allsemiconductor devices; and the strong interplay between carrier and magnetic properties allows control of the magnetic state by gating or light [7].…”