Critical exponents and irreversibility lines of La0.9Sr0.1CoO3 single crystal

Abstract

We have studied the dynamic and static critical behavior of spin glass transition in insulating La0.9Sr0.1CoO3 single crystal by ac susceptibility and dc magnetization measurements in the vicinity of its freezing temperature (T f ). The dynamic scaling analysis of the frequency dependence of ac susceptibility data yields the characteristic time constant τ0=1.6(9)×10 −12 s, the dynamic critical exponent zν=9.5(2), and a frequency dependence factor K=∆T f /T f (∆logf )=0.017, indicating that the sample enters into a canonical spin-glass phase below T f =34.8(2) K. The scaling analysis of non-linear magnetization in the vicinity of T f through the static scaling hypothesis yields critical exponents β=0.89(1) and γ=2.9(1), which match well with that observed for well known three-dimensional (3D) Heisenberg spin glasses. From the longitudinal component of zero-field-cooled and field-cooled magnetization measurement we have constructed the H − T phase diagram which represents the field evolution of two characteristic temperatures: the upper one, Tw(H), indicates the onset of spin freezing in a uniform external field H, while the lower one, Ts(H), marks the onset of strong irreversibility of the frozen state. The low field Ts(H) follows the critical line suggested by d'Almeida-Thouless model for canonical spin glass, whereas the Tw(H) exhibits a re-entrant behavior with a maximum in the Tw(H) at a nonzero field above which it follows the Gabay-Toulouse (GT) critical line which is a characteristic of Heisenberg spin glass. The reentrant behavior of the GT line resembles that predicted theoretically for n-component vector spin glasses in the presence of a uniaxial anisotropy field. PACS number(s): 75.40.Cx,75.47.Gk,71.30.+h

Pb0.65Mn2.85Ga3S8 and Pb0.72Mn2.84Ga2.95Se8: Two Quaternary Metal Chalcognides with Open-Tunnel-Framework Structures Displaying Intense Second Harmonic Generation Responses and Interesting Magnetic Properties

“…As for 2 , the FC and ZFC magnetic susceptibility data overlap very well above 10 K. Therefore, compound 2 can be assumed to be paramagnetic above 10 K. However, the divergence of FC and ZFC magnetic susceptibility below 10 K clearly illustrates the absence of long-range magnetic ordering. Moreover, the cusp at 10 K can be further regarded as a sign of the presence of short-range magnetic association and spin-glass-like state below 10 K. Note that similar magnetic behaviors have also been observed in many other spin-glass systems, such as BaFe 2 S 3 , La 0.9 Sr 0.1 CoO 3 , BiMnFe 2 O 6 , and Y 1– x Sr x MnO 3 ( x = 0.5 and 0.6)…”

Memory effects and magnetic relaxation in single-crystalline La$_{0.9}$Sr$_{0.1}$CoO$_3$

“…Earlier studies on polycrystalline compounds (0<x<0. 15) showed the presence of multiple glassy magnetic phases at low temperatures. [8][9][10] It was observed that those compounds exhibit superparamagnetic behavior originating from isolated/non-interacting FM clusters below the irreversibility temperature (T irr ) at which bifurcation of the field-cooled (FC) and zero-field-cooled (ZFC) magnetizations occurs.…”

“…8,10 Contrary to this, in single-crystalline compounds with x=0.10 and 0.15 and a highly homogeneous x=0.05 polycrystalline compound, the bifurcation of the ZFC and FC magnetization occurs close to spin freezing temperature T f and no such T irr was found and they exhibit characteristics very similar to spin glass phase. [12][13][14][15] Even at percolation threshold (x=0.18), the polycrystalline compound exhibits glassy magnetic behavior and ageing effect which are believed to be originating from both spin-glasslike phase and interacting FM clusters 16 , though the single-crystalline LSCO exhibits long-range ferromagnetic behavior with the Curie temperature T C =150 K. 17,18 Therefore, the origin of several glassy magnetic behavior in LSCO compounds for doping 0<x<0.18 is still not settled unambiguously. Compositional inhomogeneity in the polycrystalline samples could be reason for such ambiguous glassy magnetic behavior 19 and responsible for the occurrence of MEPS up to doping level as high as x=0.5.…”

“…Recently, we have studied the critical behavior of the spin glass freezing transition for the La 0.9 Sr 0.1 CoO 3 single-crystalline compound which is very close to the middle of the so called spin glass regime and showed the spin glass like phase of the compound. 15 In the present report, we have investigated its magnetic relaxation at different temperatures and magnetic fields which is an another experimental method to distinguish spin glass from that of cluster glasses and supermagnetic systems. 31,32 Indeed, our analysis of magnetic relaxations below the freezing temperature following the model proposed by Ulrich et al 32 clearly manifests a crucial difference between the phase separated state of glassy manganite and cobaltite systems.…”