Depth-dependent magnetism in epitaxial MnSb thin films: effects of surface passivation and cleaning

Abstract

Abstract. Depth-dependent magnetism in MnSb(0001) epitaxial films has been studied by combining experimental methods with different surface specificity: polarized neutron reflectivity, X-ray magnetic circular dichroism (XMCD), X-ray resonant magnetic scattering and spin-polarized low energy electron microscopy (SPLEEM). A native oxide ∼4.5 nm thick covers air-exposed samples which increases the film's coercivity. HCl etching efficiently removes this oxide and in situ surface treatment of etched samples enables surface magnetic contrast to be observed in SPLEEM. A thin Sb capping layer prevents oxidation and preserves ferromagnetism throughout the MnSb film. The interpretation of Mn L 3,2 edge XMCD data is discussed.

Heteroepitaxial Growth of Ferromagnetic MnSb(0001) Films on Ge/Si(111) Virtual Substrates

“…In Figure 6, we show hysteresis loops measured from a nominally 70 nm thick film recorded at T = 5 K. The film displays the expected ferromagnetic behavior, which is retained up to T = 300 K consistent with the reported bulk ordering temperature of MnSb T C of 314 °C. 32 The hysteresis loops in Figure 6 show the magnetic response with the applied field perpendicular and parallel to the MnSb c -axis. The data are fitted piecewise to extract the coercive field using a Langevin function to fit the hard axis and a pair of arctan functions to fit the ferromagnetic components.…”

Growth and characterisation of NiSb(0001)/GaAs(111)B epitaxial films

“…The Sb:Ni elemental ratio was found to be around 2:1, while the oxide component of the Sb and Ni peaks is clearly smaller than the main lower binding energy components and corresponds to an oxide thickness of (371) nm. Both of these results are in strong contrast to air-exposed MnSb, which has a highly Mn-rich native oxide $ 5 nm thick [26,13]. The more volatile Sb-rich oxide is easier to reduce by thermal treatment or low temperature atomic hydrogen exposure [32] making the NiSb native oxide more benign than its MnSb counterpart.…”

“…The growth of single crystal material also allows magnetocrystalline anisotropy to be exploited, which is not possible for amorphous or disordered layer structures. Extensive studies of MnSb and NiMnSb have been undertaken in recent years to elucidate their structural [10,11] and magnetic properties [12,13]. The ternary materials present greater challenges in terms of crystal growth: for example, NiMnSb may suffer from Mn surface segregation [14], atomic disorder [15] and the formation of NiSb inclusions [9], as well as difficulties in surface re-preparation [16,17].…”

EPITAXIAL GROWTH OF CUBIC MnSb ON GaAs AND InGaAs(111)

“…In this work we extend our MBE growth of MnSb from InP, 17 GaAs 18 and Ge 19 to relaxed In 0:5 Ga 0:5 As (111) virtual substrates. Furthermore, In 1Àx Ga x As structures are attractive for semiconductor spintronic applications thanks to their high electron mobility, high Land e g-factor and low Schottky barriers.…”