Strain-induced high ferromagnetic transition temperature of MnAs epilayer grown on GaAs (110).

Pengfa Xu,Guoqiang Pan,Lin Chen,Shuai Yan,Jun Lu,Jianhua Zhao,Haijuan Meng

doi:10.1186/1556-276x-6-125

Abstract

MnAs films are grown on GaAs surfaces by molecular beam epitaxy. Specular and grazing incidence X-ray diffractions are used to study the influence of different strain states of MnAs/GaAs (110) and MnAs/GaAs (001) on the first-order magnetostructural phase transition. It comes out that the first-order magnetostructural phase transition temperature Tt, at which the remnant magnetization becomes zero, is strongly affected by the strain constraint from different oriented GaAs substrates. Our results show an elevated Tt of 350 K for MnAs films grown on GaAs (110) surface, which is attributed to the effect of strain constraint from different directions.PACS: 68.35.Rh, 61.50.Ks, 81.15.Hi, 07.85.Qe

Highlights

Today, there is growing interest for realization of new technologies utilizing spin degree of freedom of electrons in semiconductor devices [1]
Experimental procedure The MnAs films were grown on GaAs (110) and GaAs (001) substrates by molecular beam epitaxy with a 12keV reflection high-energy electron diffraction (RHEED) to monitor the growth process
For MnAs films grown on GaAs (110), the buffer layer was grown at a lower substrate temperature Ts = 400°C and higher As4/Ga beam equivalent pressure (BEP) ratio of 50, while for the buffer layer grown on GaAs (001), a standard procedure (TS = 560°C, As4/Ga = 12) was used

Summary

Introduction

There is growing interest for realization of new technologies utilizing spin degree of freedom of electrons in semiconductor devices [1]. The technology of manipulating spin in semiconductors promises devices with enhanced functionality and higher speed. A prerequisite for realization of such kind of devices is development of solid-state spin injectors at room temperature. Diluted magnetic semiconductors (DMSs) and ferromagnet/semiconductor hybrids are two important components for efficient spin injection. With room-temperature ferromagnetism and high crystal quality, MnAs has been epitaxied on (001)-, (110)-, (111)-, and (113)-oriented GaAs substrates [4,5,6,7,8,9]. MnAs/GaAs having sharper interface than that of Fe/GaAs has been presented [10,11]; the sharp interface is considered to be crucial for obtaining higher transmission efficiencies. Spin injection from MnAs into GaAs has been demonstrated [12], and the spin-dependent tunneling experiments show that the spin polarization at MnAs/

Methods

Results

Conclusion