Ferromagnetism of Narrow-Gap Ge_1-x-ySn_xMn_yTe and Layered In_1-xMn_xSe Semiconductors

Abstract

Magnetic susceptibility, Hall effect and resistivity of narrow-gap Ge 1−x−y Sn x Mn y Te single crystals (x = 0.083 ÷ 0.115; y = 0.025 ÷ 0.124) were investigated in the temperature range 4.2-300 K revealing a ferromagnetic ordering at T C ≈ 50 K. Temperature dependence of magnetization indicates a superparamagnetic phase with magnetic clusters arranging in a spin glass state below the freezing temperature T f . Magnetic structure of InSe Mn 2D-ferromagnetic single crystals was studied by SQUID magnetometry, neutron diffraction, secondary ion mass spectroscopy, and wave dispersive spectra. Hysteresis loops of magnetization were observed at least up to 350 K. The cluster model of ferromagnetism is considered. The formation of self-assembled superlattice ferromagnetic InSe:Mn/antiferromagnetic MnSe during growth process and further annealing was established.

Diluted magnetic layered semiconductor InSe:Mn with high Curie temperature

“…It must result in periodical change of the manganese content in the sample cross direction. This conclusion was confirmed by SIMS investigations of Mn depth distribution [15]. In the case of (In,Mn)Se of type II sample, we have observed well pronounced oscillations of Mn content.…”

“…The exchange interaction in such clusters can occur in Mn-Se-Mn pairs and, probably, in Mn-In-Se-Mn ones [5]. Ferromagnetism was confirmed by the existence of hysteresis loops of the magnetic moment at least up to 450 K. The magnitudes of coercivity and magnetization of saturation have the same order as in the case of SQUID measurements for appropriate temperatures [15]. The Curie temperature T C of ferromagnetically ordered clusters is approximately 800 K (Fig.…”

“…In the case of (In,Mn)Se of type II sample, we have observed well pronounced oscillations of Mn content. The periods of oscillations are within the range 40 to 85 nm [15].…”

“…The further investigations of (In,Mn)Se crystals [14] explained some of their previously unclear properties such as nature of the magnetic susceptibility peaks at ~163 and 266 K. The ferromagnetic ordering with the Curie temperature T C > 350 K was revealed [15]. There appeared strong motivation to continue the study of this magnetic semiconductor.…”

“…In previous studies [14,15], we investigated the temperature dependence of the magnetic susceptibility for InSe sample containing 5 at.% Mn in the interval 2.4-300 K in the zero-field-cooled regime. Pronounced peaks at 163 and 266 K were attributed to antiferromagnetic transformations of the MnSe second phase (T N1 = 130 K, T N2 = 266 K) [19].…”