Cluster spin-glass behavior and memory effect in Cr0.5Fe0.5Ga

• Published in: Physical review. B 2018-10, Vol.98 (14), p.144436
• Main Authors: Bag, Pallab, Baral, P R, Nath, R
• Format: Article
• Language: English
• Subjects: Anisotropy; Antiferromagnetism; Clusters; Dependence; Ferromagnetism; Freezing; Magnetic induction; Magnetic permeability; Magnetic relaxation; Magnetization; Metastable state; Power law; Scaling laws; Spin dynamics; Spin glasses; Stability; Time constant; X ray powder diffraction; X-ray diffraction
• ISSN: 2469-9950; 2469-9969
• DOI: 10.1103/PhysRevB.98.144436

We report the structural, static, and dynamic properties of Cr0.5Fe0.5Ga by means of powder x-ray diffraction, dc magnetization, heat capacity, ac susceptibility, magnetic relaxation, and magnetic memory effect measurements. The dc magnetization and ac susceptibility studies reveal a spin-glass transition at around Tf≃22 K. An intermediate value of the relative shift in freezing temperature δTf≃0.017, obtained from the ac susceptibility data reflects the formation of cluster spin-glass states. The frequency dependence of Tf is also analyzed within the framework of dynamic scaling laws such as power law and Vogel-Fulcher law. The analysis using power law yields a characteristic time constant for a single spin flip τ*≃1.1×10−10 s and critical exponent zν′=4.2±0.2. On the other hand, the Vogel-Fulcher law yields the characteristic time constant for a single spin flip τ0≃6.6×10−9 s, Vogel-Fulcher temperature T0=21.1±0.1 K, and an activation energy Ea/kB≃16 K. The value of τ* and τ0 along with a nonzero value of T0 provide further evidence for the cluster spin-glass behavior. The magnetic field dependent Tf follows the de Almeida-Thouless (AT) line with a non-mean-field type instability, reflecting either a different universality class or strong anisotropy in the spin system. A detailed nonequilibrium dynamics study via relaxation and memory effect experiments demonstrates the evolution of the system through a number of intermediate metastable states and striking memory effects. All the above observations render a cluster spin-glass behavior in Cr0.5Fe0.5Ga, which is triggered by magnetic frustration due to competing antiferromagnetic and ferromagnetic interactions and magnetic site disorder. Moreover, the asymmetric response of magnetic relaxation with respect to the change in temperature, below the freezing temperature can be explained by the hierarchical model.