Spin-Glass State in $\rm CuGa_2O_4$

Magnetic-glass is a recently identified phenomenon in various classes of magnetic systems undergoing a first order magnetic phase transition. We shall highlight here a few experimentally determined characteristics of magnetic-glass and the relevant set of experiments, which will enable to distinguish a magnetic-glass unequivocally from the well known phenomena of spin-glass and reentrant spin-glass.

The magnetic field--driven transition in the spin-Peierls system CuGeO_3 associated with the closing of the spin gap is investigated numerically. The field dependence of the spin dynamical structure factor (seen by inelastic neutron scattering) and of the momentum dependent static susceptibility are calculated. In the dimerized phase (H<H_c), we suggest that the strong field dependence of the transverse susceptibility could be experimentally seen from the low temperature spin...

Strong evidences of a spin glass phase on polycrystalline RuSr2Ln1.5Ce0.5Cu2O10-x (LnRu-1222, Ln = Y, Ho and Dy) is provided by ac susceptibility and dc magnetization measurements. The fingerprint of a spin glass transition, the frequency-dependent cusp in ac susceptibility vs. T measurements at low magnetic field, is observed for all LnRu-1222 samples. The strong supression of the cusp in the ac susceptibility measurement in the presence of magnetic fields as low as 500 Oe, ...

We report magnetic properties of a 3d$^9$ (Cu$^{2+}$) magnetic insulator Cu2OSO4 measured on both powder and single crystal. The magnetic atoms of this compound form layers, whose geometry can be described either as a system of chains coupled through dimers or as a Kagom\'e lattice where every 3rd spin is replaced by a dimer. Specific heat and DC-susceptibility show a magnetic transition at 20 K, which is also confirmed by neutron scattering. Magnetic entropy extracted from t...

Spin freezing in the $A$-site spinel FeAl$_2$O$_4$ which is a spin liquid candidate is studied using remnant magnetization and nonlinear magnetic susceptibility and isofield cooling and heating protocols. The remnant magnetization behavior of FeAl$_2$O$_4$ differs significantly from that of a canonical spin glass which is also supported by analysis of the nonlinear magnetic susceptibility term $\chi_3 (T)$. Through the power-law analysis of $\chi_3 (T)$, a spin-freezing tempe...

We present muon spin rotation and relaxation ($\mu$SR) results for chalcogenide spinels CuCr$_2$X$_4$ with X= S and Se. Both compounds are known as ferromagnetic metals with high Curie temperatures. Our $\mu$SR and magnetization data show clear signatures for additional magnetic transitions far below the respective Curie temperatures. They can be related to changes in the Cr valence system from the mixed valence between Cr$^{3+}$ and Cr$^{4+}$ at high temperatures and colline...

CuMoO4 is a triclinic quantum magnet based on S = 1/2 moments at the Cu2+ site. It has recently attracted interest due to the remarkable changes in its chromic and volumetric properties at high temperatures, and in its magnetic properties at low temperatures. This material exhibits a first order structural phase transition at T_C ~ 190 K as well as a magnetic phase transition at T_N ~ 1.75 K. We report low temperature heat capacity measurements as well as extensive elastic an...

We investigate the magnetic and crystal electric field (CEF) states of the Kondo lattice system CeCuGa3 by muon spin relaxation (muSR), neutron diffraction, and inelastic neutron scattering (INS) measurements. A noncentrosymmetric BaNiSn3-type tetragonal crystal structure (space group I4mm) is inferred from x-ray as well as from neutron powder diffraction. The low-temperature magnetic susceptibility and heat capacity data show an anomaly near 2.3 - 2.5~K associated with long ...

Systematic measurements of the magnetic susceptibility were performed on single crystals of lightly doped La2-xSrxCuO4 (x=0.03, 0.04 and 0.05). For all samples the temperature dependence of the in-plane magnetic susceptibility shows typical spin-glass features with spin-glass transition temperatures Tg of 6.3K, 5.5K and 5.0K for x=0.03, 0.04 and 0.05, respectively. The canonical spin-glass order parameter extracted from the in-plane susceptibility of all the samples follows a...

The magnetic ground state of the ferromagnetic shape memory alloy of nominal composition Cu$_{2.84}$Mn$_{0.44}$Al$_{0.72}$ was investigated. The sample shows reentry of a glassy magnetic phase below the martensitic transition temperature, which is found to have complex character with two distinct anomalies in the temperature dependent ac susceptibility data. The sample retains its glassy phase even below the second transition as evident from the magnetic memory measurements i...