A long-range model with energy–spin coupling and critical properties of hexagonal antiferromagnetic manganites

Abstract

We investigate the critical properties of a model Hamiltonian involving a four-spin term with long-range interaction together with energy–spin coupling. Employing Wilson’s momentum-shell decimation scheme at one-loop order, we perform a renormalization-group analysis and obtain the critical exponents corresponding to the non-trivial fixed point. We find that the specific heat exponent α lies in the negative range in the allowed range of a parameter ρ ocurring in the four-spin long-range coupling. This predicted theoretical range is consistent with the range observed in the thermal measurements of Oleaga et al (2012 Phys. Rev. B 85 184425) in the vicinity of the Néel temperatures of various experimental samples of hexagonal antiferromagnetic manganites.

Magnetoelastic coupling and critical behavior of some strongly correlated magnetic systems

“…It is also interesting to note that experimental realization of boson lattice model with competing short-and long-range interactions in a system comprising of an atomic quantum gas trapped in an optical lattice [181] has elucidated four different quantum phases: a superfluid, a supersolid, a Mott insulator and a charge density wave. order parameter field Φ(x) and the non-conserved energy field Ψ(x), as in reference [182]. The Hamiltonian involves a nonlocal four-spin term and an energy-spin coupling, given by…”

“…Finally, the importance of spin-lattice coupling near a critical point of strongly correlated magnetic systems is discussed in section 4 with possible new directions of research. This review highlights the recent theoretical developments that have been made jointly by our group [51][52][53][54][55][56][57].…”