Related papers: Order parameters in the Verwey phase transition
The Verwey phase transition in magnetite has been analyzed using the group theory methods. It is found that two order parameters with the symmetries $X_3$ and $\Delta_5$ induce the structural transformation from the high-temperature cubic…
By combining {\it ab initio} results for the electronic structure and phonon spectrum with the group theory, we establish the origin of the Verwey transition in Fe$_3$O$_4$. Two primary order parameters with $X_3$ and $\Delta_5$ symmetries…
The order parameters of the magnetic, charge and structural orders at half-doped manganites are identified. A corresponding Landau theory of the phase transitions is formulated. Many structural and thermodynamical behaviors are accounted…
We study the possibility to apply phenomenological approach to the description of magnetic transitions in UGe$_2$ at ambient pressure with the help of Landau free energy expanded to 8th order in magnetisation. The analysis shows that for…
We describe the low temperature behaviour of the magnetic susceptibility of Cd2Re2O7 in terms of a Landau theory of structural phase transitions. We calculate the zero temperature Pauli susceptibility using a tight-binding approach to…
The magnetic phases of hexagonal perovskites RMnO_3 (R=Ho, Er, Tm, Yb, Sc, Y) are analysed using group theory and the Landau theory of phase transitions. The competition between various magnetic order parameters is discussed in the context…
A controlled point-like disorder induced by low temperature 2.5 MeV electron irradiation was used to probe the nature of the Verwey transition in magnetite, $\text{Fe}_{3}\text{O}_{4}$. Two large single crystals, one with optimal transition…
Effects of the Verwey transition on the (100) surface of magnetite were studied using scanning tunelling microscopy and spin polarized low-energy electron microsccopy. On cooling through the transition temperature Tv, the initially flat…
Polycrystalline CeGe is investigated by means of DC and AC susceptibility, non-linear DC susceptibility, electrical transport and heat capacity measurements in the low temperature regime. This compound shows two peaks at low magnetic field…
We propose a model for non isothermal ferromagnetic phase transition based on a phase field approach, in which the phase parameter is related but not identified with the magnetization. The magnetization is split in a paramagnetic and in a…
We study the possibility to apply phenomenological approach to the description of magnetic transitions in UGe2 with the help of Landau free energy expanded to 8-th order in magnetisation. The analysis shows that for certain values of…
A thorough investigation of single crystalline magnetite using broadband dielectric spectroscopy and other methods provides evidence for relaxor-like polar order in Fe3O4. We find long-range ferroelectric order to be im-peded by the…
Magnetite (Fe$_{3}$O$_{4}$), an archetypal transition metal oxide, has been used for thousands of years, from lodestones in primitive compasses[1] to a candidate material for magnetoelectronic devices.[2] In 1939 Verwey[3] found that bulk…
Seeking to unravel the enigmatic Verwey transition and its interplay with magnetism, we have conducted comprehensive measurements on the temperature-dependent electrical resistivity and magnetic moment of stoichiometric and doped-magnetite…
The phase transition to ferromagnetic order in itinerant ferromagnetic superconductor UGe$_2$ as function of pressure shows change of phase transition order. At low temperature and high pressure the transition is of first order and at…
The effect of the external field on the weakly-discontinuous first-order phase transition is analyzed in the frame of the Landau theory. The transformation of the free energy expansion as a power series in the order parameter is suggested…
By phenomenological Landau analysis, it is shown that a scalar order parameter with the point-group symmetry $\Gamma_{1g}$ explains most properties associated with the phase transition in PrFe$_4$P$_{12}$ at 6.5 K. The scalar-order model…
We investigated the electronic and vibrational properties of magnetite at temperatures from 300 K down to 10 K and for pressures up to 10 GPa by far-infrared reflectivity measurements. The Verwey transition is manifested by a drastic…
In the context of the dynamical mean-field theory of the Hubbard model, we identify microscopically an order parameter for the finite temperature Mott endpoint. We derive a Landau functional of the order parameter. We then use the order…
We present a minimal Landau theory of plastic-to-crystal phase transitions in which the key components are a multipole-moment order parameter that describes the orientational ordering of the constituent molecules, coupling between such…