Magnetic moments and anisotropies in ultrathin epitaxial Fe films on ZnSe(001)

Abstract

The morphology, atomic magnetic moments, and in-plane magnetic anisotropies of ultrathin bcc Fe͑001͒ films deposited by molecular beam epitaxy on ZnSe epilayers grown on GaAs͑001͒ single crystal are reported. The growth mode and structure have been determined in situ by means of reflection high energy electron diffraction and Auger electron spectroscopy. The magnetic properties were characterized ex situ by an alternating gradient magnetometer, superconducting quantum interference device ͑SQUID͒ magnetometry, and conversion electron Mössbauer spectroscopy ͑CEMS͒. The Fe growth is epitaxial and occurs by three dimensional nucleation at the beginning. The coalescence of the islands is observed around 7 monolayers ͑ML͒. In agreement with SQUID results, CEMS measurements indicate no reduction of the Fe magnetic moment compared to the bulk value even for the first Fe monolayers. Determination of the in-plane anisotropy constants as function of the Fe thickness shows a strong interface-induced uniaxial in-plane magnetic anisotropy, which leads to a continuous evolution from a pure uniaxial anisotropy with easy axis along ͓110͔ direction for thickness below 10 ML to the pure bulk cubic Fe anisotropy above 40 ML.

Magnetic properties of ultrathin3dtransition-metal binary alloys. I. Spin and orbital moments, anisotropy, and confirmation of Slater-Pauling behavior

“…Such thin films can exhibit substantially modified magnetic properties from the bulk, including interfacial anisotropy [15,16], strain-induced anisotropy [17][18][19], reduction of the Curie temperature [20,21], or modification of the magnetic moment [22]. While there have been a number of investigations of materials as thin films [23][24][25][26][27][28], there is not yet a comprehensive and systematic study of thin 3d transition metal alloy films that makes use of modern high-precision characterization methods-such as broad-band ferromagnetic resonance (FMR) or high-resolution x-ray diffraction (XRD). A precise measurement of the magnetic properties for this relatively simple alloy system will facilitate their use in devices, as well as the development of new alloy systems.…”

Electronic and magnetic properties of the Fe/ZnSe() interface

“…Below 8 ML the Fe film does not behave as a continuous film, but rather as an assembly of noninteracting single domain particles or clusters whose magnetization reversal is governed by thermally activated processes. The observed lack of magnetically dead layers [3] at the Fe/ZnSe interface indicates that a martensitic transition takes place. In this sense the superparamagnetic behavior of ultrathin films has probably no influence on spin injection, as the typical Fe thickness in the etherostructures employed for transport measurements are larger than 8 ML.…”

“…Due to the need of a spin-dependent interface resistance, the critical point lies on the control of the interface, which could determine such resistance. The system Fe/ZnSe(0 0 1) has been widely investigated [2,3], but the electronic and magnetic properties of the Fe film during interface formation are still poorly understood. We performed a wide analysis of such properties, by spin resolved inverse photoemission (SRIPE) and low energy electron diffraction (LEED).…”

Voltage–current hysteretic characteristic in a Ni–Cdl−Mn Te structure

“…TMR is due solely to the change of the magnetization direction of the two electrodes. Meanwhile, an ultrathin epitaxial Fe film on ZnSe was reported to significantly enhance the Fe magnetic moment [6]. This result could be of potential interest in that it could increase the probability of the injection of spin-polarized current through the metal-semiconductor interface.…”