Spin glass behavior in MnIn2Se4 and Zn1−Mn In2Se4 magnetic semiconductors

Experimental evidence of the spin-glass transition in the diluted magnetic semiconductor Zn1−xMnxIn2Se4

“…These features are evidences of collective spin freezing. As mentioned above, the negative values of the paramagnetic Curie temperature (ranging from −86 to −96 K) make evident the existence of dominant antiferromagnetic interactions in samples with x 0.87 [17]. The cusp position (T m ) indicated in figure 2(b) decreases as the Mn concentration is increased and their values are in good agreement with those obtained from EPR measurements [22].…”

“…The analysis of Mn content was determined by energy dispersive x-ray fluorescence spectroscopy (EDX) with a Shimadzu EDX-900 device. The Mn concentrations determined from EDX data are in good agreement with those extracted from magnetic measurements [16,17]. Room-temperature x-ray power-diffraction patterns indicate the formation of a pure rhombohedral structure [13] (space group R 3m) for samples with x 0.87 (see figure 1(a)) and a pure tetragonal structure (space group I 42m) (see figure 1(b)) for samples with x 0.25 [16].…”

Dynamic susceptibility measurements at the spin-glass transition in the Zn1−xMnxIn2Se4semiconductor

“…We have also checked the behaviour of the system under the influence of a dc magnetic field, H . In a Heisenberg spin glass, both strong and weak irreversible lines were first derived by Almeida and Thouless (AT) [13,20]. In Ising spin glasses, treated in the Sherrington-Kirkpatrick (SK) molecular field approximation for purely random interactions of infinite range, an H -T instability was evidenced (the AT line), which corresponds to the onset of irreversibilities with the equation…”

“…As a preliminary analysis and to facilitate the comparison with other works we chose the frequency-dependent freezing temperature, T f as the maximum of the in-phase magnetic susceptibility. The relative variation of T f per frequency decade ( T f /T f )/ log f ≈ 0.022 was determined [20]. Despite the very different structure of the present materials, ( T f /T f )/ log f is intermediate between those typically reported for metallic spin glasses (≈0.7 × 10 −2 ) [21] and for the insulator Eu 0.6 Sr 0.4 S(5 × 10 −2 ) [22], but is similar to other reported spin glasses [18,23].…”

“…In figure 4 we show the result obtained using the dynamic scaling law (equation ( 2)) for all data collection of χ ( f, T ) at different frequencies. The best data collapsing corresponds to a set of values zv = 10.7(9), β = 1.20 (20) and T c = 3.43(1) K for MnIn 2 Se 4 (x = 1.0), and zv = 9.7(1.0), β = 1.18 (20) and T c = 2.61(6) K for the sample with x = 0.87. These values are in good agreement with these previously published for semimagnetic systems [29,30], and also with data obtained by numerical simulation for the case of three-dimensional spin glasses with short range interactions [15].…”