— With the help of exact ground states obtained by a polynomial algorithm we compute the domain wall energy ∆ at zero-temperature for the bond-random and the site-random Ising spin glass model in two dimensions. We find that in both models the stability of the ferromagnetic and the spin glass order ceases to exist at a unique concentration pc for the ferromagnetic bonds. In the vicinity of this...

Slow spin dynamics has been observed in superconducting under-doped Ca0.9Ce0.1Fe2As2 single crystal. Below 100 K, the system exhibits hysteresis in the cooling and warming protocols of temperature dependent resistivity due to first order tetragonal to orthorhombic structural transition with simultaneous magnetic transition from paramagnetic to spin density wave antiferromagnetic state of the ir...

Pressure dependknce of XAC (T) for amorphous Fe,Laloo-, has been measured up to 20 kbar. With increasing pressure, the ferromagnetic phase for x = 87.5 reduces and finally the spin-glass state is realized below 110 K. Paramagnetic to spin-glass transition temperature observed for x = 92.5 becomes low by applying pressure. Spin-glass behavior has been observed in Fe-rich amorphous alloy systems ...

We show strong evidence for the absence of a finite-temperature spin glass transition for the random-bond Ising model on self-dual lattices. The analysis is performed by an application of duality relations, which enables us to derive a precise but approximate location of the multicritical point on the Nishimori line. This method can be systematically improved to presumably give the exact result...

Abstract. We consider a long-range Ising antiferromagnet (LRIAF) put in a transverse field. Applying quantum Monte Carlo method, we study the variation of order parameter (spin correlation in Trotter time direction), susceptibility and average energy of the system for various values of the transverse field at different temperatures. The antiferromagnetic order is seen to get immediately broken ...

we report on the synthesis, morphology, chemically and structurally of tio2-nio-sio2 nanostructure. the tio2-nio-sio2 nanostructure was synthesized by a method based on the sol-gel method, by the simultaneous gelation of all cations. the coatings were deposited on dried soda-lime glass slides by spin coating. composite powders and coating on glass have been characterized by xrd, sem, edax, and ...

We discuss the slow, nonequilibrium, dynamics of spin glasses in their glassy phase. We briefly review the present theoretical understanding of the spectacular phenomena observed in experiments and describe new numerical results obtained in the first large-scale simulation of the nonequilibrium dynamics of the three-dimensional Heisenberg spin glass. 1. Why do we study spin glass dynamics? Spin...

The Kondo-Spin Glass competition is studied in a theoretical model of a Kondo lattice with an intra-site Kondo-type exchange interaction treated within the mean-field approximation, an inter-site quantum Ising exchange interaction with random couplings among localized spins and an additional transverse field Γ in the x-direction, which represents a simple quantum mechanism of spin flipping, in ...

Ising spin-glass systems with long-range interactions (J(r) ∼ r) are considered. A numerical study of the critical behaviour is presented in the non-mean-field region together with an analysis of the probability distribution of the overlaps and of the ultrametric structure of the space of pure states in the frozen phase. Also in presence of diverging thermodynamical fluctuations at the critical...

We present new magnetic heat capacity and neutron scattering results for two magnetically frustrated molybdate pyrochlores: S=1 oxide Lu_{2}Mo_{2}O_{7} and S=1/2 oxynitride Lu_{2}Mo_{2}O_{5}N_{2}. Lu_{2}Mo_{2}O_{7} undergoes a transition to an unconventional spin glass ground state at T_{f}∼16  K. However, the preparation of the corresponding oxynitride tunes the nature of the ground state from...