Related papers: Helicity Order: Hidden Order Parameter in URu$_2$S…
A comprehensive transport study, as a function of both temperature and magnetic field in continuous magnetic fields up to 45 T reveals that URu2Si2 possesses all the essential hallmarks of quantum criticality at temperatures above 5.5 K and…
Motivated by experiment, we review the case for phase inhomogeneity in URu_2Si_2. In this scenario, the paramagnetic hidden order phase coexists with small distinct domains of antiferromagnetism whose volume fraction increases with…
Substitution of Re for Ru in the heavy fermion compound URu2Si2 suppresses the hidden order transition and gives rise to ferromagnetism at higher concentrations. The hidden order transition of URu(2-x)Re(x)Si2, tracked via specific heat and…
The observation of Ising quasiparticles is a signatory feature of the hidden order phase of URu$_2$Si$_2$. In this paper we discuss its nature and the strong constraints it places on current theories of the hidden order. In the hastatic…
Recent experimental and theoretical interest in the superconducting phase of the heavy fermion material URu$_2$Si$_2$ has led to a number of proposals in which the superconducting order parameter breaks time-reversal symmetry (TRS). In this…
We have carried out a careful magnetic neutron scattering study of the heavy fermion compound \URuSi\ to probe the possible existence of a small magnetic moment parallel to tetragonal basal plane in the "hidden-order" phase. This small…
Heavy electronic states originating from the f atomic orbitals underlie a rich variety of quantum phases of matter. We use atomic scale imaging and spectroscopy with the scanning tunneling microscope (STM) to examine the novel electronic…
We studied the uniaxial-pressure dependence of the resistivity for URu$_{2-x}$Fe$_x$Si$_2$ samples with $x$ = 0 and 0.2, which host a hidden order (HO) and a large-moment antiferromagnetic (LMAFM) phase, respectively. For both samples, the…
The weak antiferromagnetism of URu${}_{2}$Si${}_{2}$ is discussed on the basis of a duality model which takes into account salient features of both itinerant fermions and "localized" component of spin degrees of freedom. The problem is…
We report simultaneous measurements of the distribution of lattice constants and the antiferromagnetic moment in high-purity URu2Si2, using both Larmor and conventional neutron diffraction, as a function of temperature and pressure up to 18…
The temperature dependent order parameter provides important information on the nature of magnetism. Using traditional methods to study this parameter in two-dimensional (2D) magnets remains difficult, however, particularly for insulating…
By means of neutron scattering we show that the high-temperature precursor to the hidden order state of the heavy fermion superconductor URu$_{2}$Si$_{2}$ exhibits heavily damped incommensurate paramagnons whose strong energy dispersion is…
A review of recent state-of-the-art pulsed field experiments performed on URu$_2$Si$_2$ under a magnetic field applied along its easy magnetic axis $\mathbf{c}$ is given. Resistivity, magnetization, magnetic susceptibility, Shubnikov-de…
We compute and compare even- and odd-parity superconducting order parameters of strontium ruthenate ($\mathrm{Sr}_2\mathrm{RuO}_4$) in the limit of weak interactions, resulting from a fully microscopic three-dimensional model including…
A magnetic order in orthorhombic GdCu$_2$ was investigated via a single crystal neutron diffraction with thermal neutron. Magnetic peaks were observed at incommensurate positions described by the ordering vector $q$=(${\delta}$,~1,~0) with…
Electronic structure calculations obtained with an approach with density functional theory with an enhanced local Coulomb interaction, DFT+$U$, are presented for the relativistic magnetic insulator Sr$_{2}$IrO$_{4}$. The results are in…
We use inelastic neutron scattering measurements to show that the energy gap in the magnetic excitations of URu$_2$Si$_2$, induced by the Hidden Order transition, is closed by Re substitution. The magnetic excitations remain ungapped in…
The recent experimental finding of large-amplitude antiferromagnetism induced by uniaxial strain shows that the "hidden" low-field order of URu2Si2 breaks time reversal invariance. We propose a new crystal field model which supports…
A series of Sr(Co$_{1-x}$Ni$_x$)$_2$As$_2$ single crystals was synthesized allowing a comprehensive phase diagram with respect to field, temperature, and chemical substitution to be established. Our neutron diffraction experiments revealed…
The concept of the order parameter is extremely useful in physics. Here, I discuss extensions of this concept to cases when the order parameter is no longer a constant but fluctuates or oscillates in space and time. This allows one to…