On the origin of magnetism in (Ga,Mn)As: from paramagnetic through superparamagnetic to ferromagnetic phase

Abstract

The high-spectral-resolution spectroscopic studies of the energy gap evolution, supplemented with electronic, magnetic and structural characterization, show that the modification of the GaAs valence band caused by Mn incorporation occurs already for a very low Mn content, much lower than that required to support ferromagnetic spin - spin coupling in (Ga,Mn)As. Only for n-type (Ga,Mn)As with the Mn content below about 0.3% the Mn-related extended states are visible as a feature detached from the valence-band edge and partly occupied with electrons. The combined magnetic and low-temperature photoreflectance studies presented here indicate that the paramagnetic - ferromagnetic transformation in p-type (Ga,Mn)As takes place without imposing changes of the unitary character of the valence band with the Fermi level located therein. The whole process is rooted in the nanoscale fluctuations of the local (hole) density of states and the formation of a superparamagnetic-like state. The Fermi level in (Ga,Mn)As is coarsened by the carrier concentration of the itinerant valence band holes and further fine-tuned by the many-body interactions.

References in corpus (37)

• Hole-mediated ferromagnetism in tetrahedrally coordinated semiconductors
• Ferromagnetism in semiconductors and oxides: prospects from a ten years' perspective
• Dilute ferromagnetic semiconductors: Physics and spintronic structures
• Prospects of high temperature ferromagnetism in (Ga,Mn)As semiconductors
• Visualizing Critical Correlations near the Metal-Insulator Transition in Ga1-xMnxAs
• Experimental probing of the interplay between ferromagnetism and localisation in (Ga,Mn)As
• In-plane uniaxial anisotropy rotations in (Ga,Mn)As thin films
• Sensitive SQUID magnetometry for studying nano-magnetism
• Nonvolatile ferroelectric control of ferromagnetism in (Ga,Mn)As
• On the character of states near the Fermi level in (Ga,Mn)As: impurity to valence band crossover
• Origin of the anomalous magnetic circular dichroism spectral shape in ferromagnetic (Ga,Mn)As: Impurity bands inside the band gap
• Interplay between carrier localization and magnetism in diluted magnetic and ferromagnetic semiconductors
• Unveiling the impurity band inducing ferromagnetism in magnetic semiconductor (Ga,Mn)As
• Ellipsometric study of the Electronic Structure of GaMnAs and LT-GaAs
• Onset of ferromagnetism in low-doped GaMnAs
• Influence of defects on the lattice constant of GaMnAs
• Electron correlations in Mn${}_x$Ga${}_{1-x}$As as seen by resonant electron spectroscopy and dynamical mean field theory
• Light-induced magnetization precession in GaMnAs
• Systematic study of magnetic linear dichroism and birefringence in (Ga,Mn)As
• Identifying the electronic character and role of the Mn states in the valence band of (Ga,Mn)As
• Temperature and magnetization-dependent band-gap renormalization and optical many-body effects in diluted magnetic semiconductors
• Magnetic anisotropy of epitaxial (Ga,Mn)As on (113)A GaAs
• All-wurtzite (In,Ga)As-(Ga,Mn)As core-shell nanowires grown by molecular beam epitaxy
• Photoreflectance Study of the Fundamental Optical Properties of (Ga,Mn)As Epitaxial Films
• Formation process and superparamagnetic properties of (Mn,Ga)As nanocrystals in GaAs fabricated by annealing of (Ga,Mn)As layers with low Mn content
• An infrared probe of the insulator-to-metal transition in GaMnAs and GaBeAs
• Fermi level position, Coulomb gap, and Dresselhaus splitting in (Ga,Mn)As
• Hydrostatic pressure study of paramagnetic-ferromagnetic phase transition in (Ga,Mn)As
• Anomalous Fermi level behavior in GaMnAs at the onset of ferromagnetism
• Ferromagnetism and infrared electrodynamics of Ga${}_{1-x}$Mn${}_x$As}
• Electronic- and band-structure evolution in low-doped (Ga,Mn)As
• Wurtzite (Ga,Mn)As nanowire shells with ferromagnetic properties
• Effect of low-temperature annealing on the electronic- and band-structure of (Ga,Mn)As epitaxial layers
• Transport through (Ga,Mn)As nanoislands: Coulomb-blockade and temperature dependence of the conductance
• Electronic structure of (Ga,Mn)As revisited
• Hole sp3-character and delocalization in (Ga,Mn)As revised with pSIC and MLWF approaches - newly found spin-unpolarized gap states of s-type below 1% of Mn
• Alternative interpretation of the recent experimental results of angle-resolved photoemission spectroscopy on GaMnAs [Sci. Rep. 6, 27266 (2016)]

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