Spin-glass-like behavior of Ge:Mn

Abstract

We present a detailed study of the magnetic properties of low-temperature molecular beam epitaxy grown Ge:Mn dilute magnetic semiconductor films. We find strong indications for a frozen state of Ge 1−x Mn x , with freezing temperatures of T f = 12 K and T f = 15 K for samples with x = 0.04 and x = 0.2, respectively, determined from the difference between field cooled and zero-field cooled magnetization. For Ge 0.96 Mn 0.04 , AC susceptibility measurements show a peak around T f , with the peak position T ′ f shifting as a function of the driving frequency f by ∆T ′ f /[T ′ f · ∆logf ] ≈ 0.06, whereas for sample Ge 0.8 Mn 0.2 a more complicated behavior is observed. Furthermore, both samples exhibit relaxation effects of the magnetization after switching the magnitude of the external magnetic field below T f which are in qualitative agreement with the field and zero-field cooled magnetization measurements. These findings consistently show that Ge:Mn exhibits a frozen magnetic state at low temperatures, and that it is not a conventional ferromagnet.

Magnetic Nature of a Ni Dopant in La1.85Sr0.15CuO4: Spin-Glass Behavior

“…In the case of superparamagnets, below the blocking temperature T b of independent superparamagnetic entitles (either single ions or clusters) the FC magnetization continues to increase with decreasing temperature, while for LSCNO we observe relatively flat magnetization below the bifurcation temperature of χ(T ) curve. However, when the interaction between single entities occurs in the superparamagnetic system, it can be difficult to distinguish between such an interacting superparamagnet and a real spin glass exhibiting a thermodynamic phase transition [5]. Let us note that the temperature of maximum in the ZFC χ(T ) curve, T g , is slightly below T irr (in Fig.…”

Diffuse x-ray scattering from inclusions in ferromagneticGe1−xMnxlayers

“…Among these systems GeMn is most probably the so far best investigated [2][3][4][5][6][7][8][9][10][11][12][13] providing local ferromagnetic transition temperatures well above 100 K 7,9 and above roomtemperature global ferromagnetic transition temperatures. 8,10 A common approach to fabricate Ge 1−x Mn x layers on Ge substrates is the codeposition of Ge and Mn in low substrate temperature, solid source molecular-beam epitaxy ͑LT-MBE͒.…”

Hydration-induced spin-glass state in a frustrated Na-Mn-O triangular lattice

“…x Mn x [49] or the La(Fe 1-x Mn x ) 11.4 Si 1.6 compounds [50]. In view of this, quantifying the frequency shift of the T f , measured as the relative variation of χ'(T) peak-temperature position per frequency (ω= 2πf) decade…”