Magnetic properties of the layered III-VI diluted magnetic semiconductor Ga1−xFexTe

T M Pekarek,I Miotkowski,A K Ramdas,P S Edwards,C Lampropoulos,T L Olejniczak

doi:10.1063/1.4945335

T M Pekarek, I Miotkowski + Show 4 more

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https://doi.org/10.1063/1.4945335

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Abstract

Magnetic properties of single crystalline Ga1−xFexTe (x = 0.05) have been measured. GaTe and related layered III-VI semiconductors exhibit a rich collection of important properties for THz generation and detection. The magnetization versus field for an x = 0.05 sample deviates from the linear response seen previously in Ga1−xMnxSe and Ga1−xMnxS and reaches a maximum of 0.68 emu/g at 2 K in 7 T. The magnetization of Ga1−xFexTe saturates rapidly even at room temperature where the magnetization reaches 50% of saturation in a field of only 0.2 T. In 0.1 T at temperatures between 50 and 400 K, the magnetization drops to a roughly constant 0.22 emu/g. In 0 T, the magnetization drops to zero with no hysteresis present. The data is consistent with Van-Vleck paramagnetism combined with a pronounced crystalline anisotropy, which is similar to that observed for Ga1−xFexSe. Neither the broad thermal hysteresis observed from 100-300 K in In1−xMnxSe nor the spin-glass behavior observed around 10.9 K in Ga1−xMnxS are observed in Ga1−xFexTe. Single crystal x-ray diffraction data yield a rhombohedral space group bearing hexagonal axes, namely R3c. The unit cell dimensions were a = 5.01 Å, b = 5.01 Å, and c = 17.02 Å, with α = 90°, β = 90°, and γ = 120° giving a unit cell volume of 369 Å3.

Highlights

The data is consistent with Van-Vleck paramagnetism combined with a pronounced crystalline anisotropy, which is similar to that observed for Ga1−xFexSe
Magnetization versus temperature measurements taken on a single crystalline Ga1−xFexTe sample with a magnetic field oriented perpendicular to the two-dimensional GaTe layers are shown in Figs. 1(a) and 1(b)
The long-range interaction of spins in Ga1−xFexTe apparently does not play the same prominent role in Ga1−xFexTe that the transition metal ions play in related III-VI DMS systems

Summary

INTRODUCTION

Gallium selenide (GaSe) has emerged as one of the best non-linear optical materials.[1,2,3,4,5,6,7,8,9,10,11] GaSe exhibits a rich collection of important properties for THz generation and detection applications including a large non-linear coefficient, high damage threshold, high-temperature operation, and a wide transparency range.[1,2,3,4] GaSe is highly efficient as a broadband tunable source up to 40 THz and as a sensor up to 100 THz.[4,5] In short, GaSe (and related doped and un-doped III-VI semiconductors such as GaTe) have emerged as valuable systems in the very active THz research field.[1,2,3,5,6,8,9,10,11] Work on GaTe and doped GaTe crystals includes the growth and characterization of these systems for broadband tunable THz sources and sensors.[5]. The In doping did not degrade the useful properties of GaSe but resulted in enhanced non-linear optical properties.[2,3,5,6,8,9,10,11] First-principles theoretical studies investigating the mechanical and electrical properties Te-based systems were conducted.[3]. Unlike doping with In, the incorporation of a transition metal element raises intriguing possibilities for coupling the magnetic properties of the transition metal ion with the host III-VI semiconductor leading to optical or electrical transport effects. Transition metal ion Cr in Ga1−xCrxSe2,6 has already been studied and shows improved mechanical properties while preserving the advantages of the host GaSe as a THz material.[2,6]. This work complements work done on the other III-VI DMS systems investigated to date (Ga1−xMnxS,[14,15,16,17,18] In1−xMnxS,[19,20] In1−xMnxSe,[21,22,23] Ga1−xMnxSe,[24] and Ga1−xFexSe).[25]

EXPERIMENTAL DETAILS

EXPERIMENTAL RESULTS AND DISCUSSION

CONCLUSIONS