Related papers: Symmetry Analysis for the Ruddlesden-Popper System…
The magnetic phase diagram and the thermodynamic properties of a square lattice containing antiferromagnetically coupled spin-1/2 triangles are studied. A Heisenberg Hamiltonian with three strong intra-triangle exchange coupling constants…
The nature of the pseudogap phase is a central problem in the quest to understand high-Tc cuprate superconductors. A fundamental question is what symmetries are broken when that phase sets in below a temperature T*. There is evidence from…
Several rare earth magnetic pyrochlore materials are well modeled by a spin-1/2 quantum Hamiltonian with anisotropic exchange parameters Js. For the Er2Ti2O7 material, the Js were recently determined from high-field inelastic neutron…
A detailed analysis of the crystal structure in RETiO3 with RE = La, Nd, Sm, Gd, and Y reveals an intrinsic coupling between orbital degrees of freedom and the lattice which cannot be fully attributed to the structural deformation arising…
The notion of a simple ordered state implies homogeneity. If the order is established by a broken symmetry, elementary Landau theory of phase transitions shows that only one symmetry mode describes this state. Precisely at points of phase…
We propose the Landau model for lock-in phase transitions in uniaxially modulated improper ferroelectric incommensurate-commensurate systems of class I. It includes Umklapp terms of third and fourth order and secondary order parameter…
The lattice instabilities of perovskite structure oxides are responsible for many of their interesting properties, such as temperature-dependent ferroelectric phase transitions. First-principles calculations using linear response theory…
The low temperature properties of the Kagome-type system Co3V2O8 have been studied by powder neutron diffraction both in zero field and in applied magnetic field of up to 8 T. Below 6 K, the zero-field ground state is ferromagnetic with the…
We report ultra-low-temperature $^{23}$Na NMR measurements on the Ising triangular lattice antiferromagnet Na$_2$BaCo(PO$_4$)$_2$, which precisely resolve the phase diagram under magnetic field applied along the crystalline $c$ axis. With…
The magnetic and structural properties of MnAs are studied with ab initio methods, and by mapping total energies onto a Heisenberg model. The stability of the different phases is found to depend mainly on the volume and on the amount of…
In the triangular layered magnet PdCrO2 the intralayer magnetic interactions are strong, however the lattice structure frustrates interlayer interactions. In spite of this, long-range, 120$^\circ$ antiferromagnetic order condenses at $T_N =…
The crystal and magnetic structures of the nitride antiperovskite Mn$_3$GeN reveals ferrimagnetic order stemming from a distorted kagome-derived lattice of the Mn atoms. Polycrystalline Mn$_3$GeN was synthesized via a solid-state reaction…
UPd$_3$ is known to exhibit four antiferroquadrupolar ordered phases at low temperatures. We report measurements of the magnetisation and magnetostriction of single crystal UPd$_3$, along the principal symmetry directions, in fields up to…
We report a detailed investigation into the metamagnetism of Sr3Ru2O7 at low temperatures for the magnetic field parallel to the ruthenium oxygen planes. The metamagnetism is studied as a function of temperature, magnetic field and sample…
The strategic design of ferroelectric materials exhibiting robust and reversible spontaneous polarization remains a pivotal challenge in functional materials research. Here, A-site cation disorder engineering is employed in the n = 2…
The two-dimensional Ising model on a distorted Kagom\'{e} lattice is studied by means of exact solutions and the tensor renormalisation group (TRG) method. The zero-field phase diagrams are obtained, where three phases such as…
The phase purity and crystal structure of PLTA samples (synthesized via sol-gel process) were confirmed using synchrotron x-ray powder diffraction (wavelength, lmbda= 0.44573 A. Rietveld analyses of powder x-ray diffraction data confirmed…
Ordering of the classical Heisenberg antiferromagnet on the triangular lattice is studied by means of a mean-field calculation, a scaling argument and a Monte Carlo simulation, with special attention to its vortex degree of freedom. The…
Contrary to canonical expectations we show that lattice translational symmetry breaking often accompanies uniformly ordered flux phases. We demonstrate this phenomena by studying a spinless-fermion model on a square latttice with…
In order to investigate quantum and thermal phase transitions in the Bechgaard salts and their sulfur analogs, we perform finite-temperature Hartree-Fock calculations in one dimension with particular emphasis on the interplay between charge…