Transversal spin freezing and re-entrant spin glass phases in chemically disordered Fe-containing perovskite multiferroics

Abstract

We propose experimental verification and theoretical explanation of magnetic anomalies in the complex Fe-contained double perovskite multiferroics like PbFe 1/2 Nb 1/2 O3. The theoretical part is based on our model of coexistence of long-range magnetic order and spin glass in the above substances. In our model, the exchange interaction is anisotropic, coupling antiferromagnetically z spin components of Fe 3+ ions. At the same time, the xy components are coupled by much weaker exchange interaction of ferromagnetic sign. In the system with spatial disorder (half of corresponding lattice cites are occupied by spinless Nb 5+ ions) such frustrating interaction results in the fact that antiferromagnetic order is formed by z projection of the spins, while their xy components contribute to spin glass behaviour. Our theoretical findings are supported by the experimental evidence of coexistence of antiferromagnetic and spin glass phases in chemically disordered Fe-contained double perovskite multiferroics.

Lévy flights in an infinite potential well as a hypersingular Fredholm problem

“…substances, combining several types of longrange orders (like ferroelectricity and ferromagnetism). The non-Gaussian statistics due to disorder plays an important role in these substances also [59,60] and we are applying now our formalism (also in context of the problem of quantum oscillator with fractional Laplacian) to obtain the adequate description of their physical properties.…”

Magnetoelectric effect in antiferromagnetic multiferroic Pb(Fe1/2Nb1/2Laguta1, Stephanovich2, Raevski3 et al. 2017Phys. Rev. BSelf Cite410121View full textAdd to dashboardCite

“…[3,8]). On the other hand, the ME coefficient does not show the sign reversal at the transition from the paramagnetic phase to the spin glass state.…”

“…The latter coexistence has recently been studied in details both experimentally and theoretically [3,8].…”

Fractional Quantum Oscillator And Disorder In The Vibrational Spectra

“…A compelling example is the properties of the above multiferroics [5]. The non-Gaussian statistics due to disorder and frustration plays an important role in these substances [28,29,30] and it is challenging to apply the above formalism to explain their disorder (in phonon and magnon subsystems) phenomenologically in terms of introduction fractional derivatives to the corresponding Schrödinger equations. The dynamics of such "disordered phonons and magnons" can be described in terms of the above FP equation.…”