相关论文: Multiferroic quantum criticality in (Eu,Ba,Sr)TiO$…
The zero-temperature limit of a continuous phase transition is marked by a quantum critical point, which can generate exotic physics that extends to elevated temperatures. Magnetic quantum criticality is now well known, and has been…
Materials tuned to the neighbourhood of a zero temperature phase transition often show the emergence of novel quantum phenomena. Much of the effort to study these new effects, like the breakdown of the conventional Fermi-liquid theory of…
We discuss the interplay between anti-ferromagnetic order and polarization fluctuations in a magnetic quantum paraelectric. Using an action where anti-ferromagnetic order parameter couples to the polarization fluctuations and as well as…
The bulk magnetic susceptibility $\chi(T,B)$ of YbRh$_2$(Si$_{0.95}$Ge$_{0.05}$)$_2$ has been investigated %by ac-and dc-magnetometry at low temperatures and close to the field-induced quantum critical point at $B_c=0.027$ T. For $B\leq…
Tris-sarcosine calcium chloride (TSCC) is a highly uniaxial ferroelectric with a Curie temperature of approximately 130K. By suppressing ferroelectricity with bromine substitution on the chlorine sites, pure single crystals were tuned…
Several quantum critical compounds have been argued to have multiple instabilities towards orders with distinct dynamical exponents. We present an analysis of a quantum multicritical point in an itinerant magnet with competition between…
A realistic theory of the quantum paraelectric - ferroelectric transition is presented, involving parameters determined from band calculations and a renormalization group treatment of critical fluctuations. The effects of reduced…
Measurements of ferroelectric polarization and dielectric constant were done on $R$Mn$_2$O$_5$ ($R$=Tb, Dy, and Ho) with applied hydrostatic pressures of up to 18 kbar. At ambient pressure, distinctive anomalies were observed in the…
Temperature measurements of dielectric permittivity are performed for nonstoichiometric ferroelectric lead germanate Pb$_{4.95}$Ge$_3$O$_{11}$ and multiferroic solid solution [N(C$_2$H$_5$)$_4$]$_2$CoClBr$_3$. Unlike the heat capacity data,…
Specific heat studies of the Sr$_{1-x}$Ba$_x$Mn$_{1-y}$Ti$_y$O$_3$ polycrystalline samples performed by the relaxation and DSC methods over the temperature range 2 - 450 K are reported. Anomalies accompanying the…
The transverse field Ising chain (TFIC) model is ideally suited for testing the fundamental ideas of quantum phase transitions, because its well-known $T=0$ ground state can be extrapolated to finite temperatures. Nonetheless, the lack of…
Quantum-critical behavior of the itinerant electron antiferromagnet (V0.9Ti0.1)2O3 has been studied by single-crystal neutron scattering. By directly observing antiferromagnetic spin fluctuations in the paramagnetic phase, we have shown…
We report on neutron diffraction, thermal expansion, magnetostriction, dielectric, and specific heat measurements on polycrystalline FeCr2S4 in external magnetic fields. The ferrimagnetic ordering temperatures $T_{\mathrm{C}}\approx 170$ K…
The effect of ferroelectric fluctuations on the temperature dependent dielectric constant of SrTiO$_3\,$(STO) has been long studied. Those fluctuations have been shown in recent years to be quantum critical and STO demonstrated to form the…
Dielectric and magnetic properties of Eu0.5Ba0.25Sr0.25TiO3 are investigated between 10 K and 300 K in the frequency range from 10 Hz to 100 THz. A peak in permittivity revealed near 130 K and observed ferroelectric hysteresis loops prove…
Unconventional metallic states which do not support well defined single-particle excitations can arise near quantum phase transitions as strong quantum fluctuations of incipient order parameters prevent electrons from forming coherent…
In this work we explore the overall structural behaviour of the [(CH3)2NH2][Mn(HCOO)3] multiferroic compound across the temperature range where its ferroelectric transition takes place by means of calorimetry, thermal expansion measurements…
We report combined magnetic susceptibility, dielectric constant, nuclear quadruple resonance (NQR) and zero-field nuclear magnetic resonance (NMR) measurements on single crystals of multiferroics CuBr$_2$. High quality of the sample is…
Entanglement of two different quantum orders is of an interest of the modern condensed matter physics. One of the examples is the dynamical multiferroicity, where fluctuations of electric dipoles lead to magnetization. We investigate this…
As a paradigmatic example of multi-scale quantum criticality, we consider the Pomeranchuk instability of an isotropic Fermi liquid in two spatial dimensions, d=2. The corresponding Ginzburg-Landau theory for the quadrupolar fluctuations of…