Magnetic impurity bands in Ga1−xMnxS : Towards understanding the anomalous spin-glass transition

Abstract

We report on the magnetic and electronic properties of single crystalline Ga0.91Mn0.09S, which is a quasi-two-dimensional diluted magnetic semiconductor. Through an analysis of magnetization data, we show the existence of an anomalously high spin-glass transition temperature at 11.2 K. Using density functional theory (DFT), we characterize the properties contributing to the spin-glass transition through an examination of the electronic and magnetic properties for Ga1−xMnxS with x varying from 0.00 to 0.18 by randomly substituting Mn atoms into the gallium (Ga) lattice sites. We show that the presence of magnetic atoms produces impurity bands in the electronic structure, where an analysis of the density of states shows an increase in magnetic impurity bands at the Fermi level that lowers the semiconducting gap and is consistent with diluted magnetic semiconductors. Furthermore, this indicates that the spin-glass transition in Ga0.91Mn0.09S is similar to other DMS materials, where the primary mechanism is likely through magnetic exchange. However, the increased electron density in the system with Mn doping could explain the anomalously higher spinglass transition temperature in Ga0.91Mn0.09S. In comparison with the substantially lower transition temperatures in related II-VI based systems (i.e., Zn1−xMnxTe), the high transition temperature is typically associated with more metallic spin-glass systems that interact through RKKY exchange, which leads to the conclusion that there may be a combination of interactions occurring in these systems. Further measurements on the other substitution percentages will hopefully clarify these interactions.

Irreversible heat flow across phase boundaries in phase-separated manganites

“…Further examination of the heat loss in the phase-separated regime might allow further insight into the nature of the transition from the dynamic phase-separated state into the static phaseseparated state. This transition between a dynamic and static phase-separated state has been observed in the LPCMO, Ni-Ti alloys [20], and Fe-Pd alloys [9], systems in analogy with the glass 10 transition in pure spin systems [21] and in solids [22][23][24][25][26]. Strain is suggested to be the mediating variable in realizing this type of glass transition because it is intrinsic to a phase-separated system in the solid state where the two phases have different structures.…”

Enhancement of the spin-glass transition temperature through pd -orbital hybridization in Zn1−xMnxTeAlcantara1, Barrett2, Matev3 et al. 2021Phys. Rev. BSelf Cite1000View full textAdd to dashboardCite

“…The cusp is observed to shift to lower temperatures in the 1 and 2 T fields. The top inset of (a) shows a universal scaling fit of non-linear magnetization for our previous data on Ga0.91Mn0.09S and Zn0.49Mn0.51Te that was able to definitively confirm the transition to the spin-glass state [10,21].…”

“…As shown in Fig. 1, spinglass materials can be metals, insulators, and semicon- ductors [7][8][9][10][11][12][13][14][15][16][17][18][19][20][21][22][25][26][27][28][29][30][31][32], where one clue to their formation comes from the fact that the transition temperature of spin-glasses increases with carrier density and electronic mobility, which indicates a need for distinct orbital interactions.…”

“…Many of these materials produce robust semiconducting states and have been used in solar cells and electronic components. Doping these chalcogenide materials with moderate amounts of magnetic transition-metal elements have been shown to produce diluted magnetic semiconductors [10][11][12][13][14][15][16][17][18][19][20][21][22]. More interestingly, many of these materials exhibit spin-glass behavior.…”

Dirac Nodes and Magnetic Order in M2X2 Transition‐Metal Chalcogenides

“…Experimental results from gallium sulfide and selenide (Ga 2 S 2 and Ga 2 Se 2 ) studies show that transition‐metal impurities change the electronic and magnetic structure . While these materials are typically dilute magnetic semiconductors, the substitution of transition‐metal atoms into the Ga sites has been shown to change the electronic structure through the interactions between the localized magnetic moments and the formation of impurity bands near the Fermi level . Therefore, it is proposed that the complete substitution of the M sites with transition‐metal elements (M = Cr, Mn, and Fe) may result in both a distinct magnetic moment and Dirac nodes.…”