Related papers: Spin-orbit density wave induced hidden topological…
Phase transitions and symmetry are intimately linked. Melting of ice, for example, restores translation invariance. The mysterious hidden order (HO) phase of URu$_2$Si$_2$ has, despite relentless research efforts, kept its symmetry breaking…
The Fermi surface (FS) nesting properties of URu$_2$Si$_2$ are analyzed with particular focus on their implication for the mysterious hidden order phase. We show that there exist two Fermi surfaces that exhibit a strong nesting at the…
We argue that near a Kondo breakdown critical point, a spin liquid with spatial modulations can form. Unlike its uniform counterpart, we find that this occurs via a second order phase transition. The amount of entropy quenched when ordering…
We present the theory of a new type of topological quantum order which is driven by the spin-orbit density wave order parameter, and distinguished by $Z_2$ topological invariant. We show that when two oppositely polarized chiral bands…
This Topical Review describes the multitude of unconventional behaviors in the hidden order, heavy fermion, antiferromagnetic and superconducting phases of the intermetallic compound URu$_2$Si$_2$ when tuned with pressure, magnetic field,…
We report $^{29}$Si NMR measurements in single crystals and aligned powders of URu$_2$Si$_2$ in the hidden order and paramagnetic phases. The spin-lattice-relaxation data reveal evidence of pseudospin fluctuations of U moments in the…
A systematic search for possible order parameters of the so-called hidden order of URu$_{2}$Si$_{2}$ is conducted. Among the possible candidates that do fulfill the experimental symmetry restrictions on the hidden order parameter, we find…
Complex electronic matter exhibit subtle forms of self organization which are almost invisible to the available experimental tools, but which have dramatic physical consequences. One prominent example is provided by the actinide based heavy…
Motivated by experiment, we argue that the enigmatic hidden order in $URu_2Si_2$ demands a dual description that encompasses both its itinerant and its local aspects. A combination of symmetry considerations and observation allow us to rule…
The tetragonal heavy-fermion compound CeAuSb$_2$ (space group $P4/nmm$) exhibits incommensurate spin density wave (SDW) order below $T_{N}\approx6.5~K$ with the propagation vector $\mathbf{q}_A = (\delta_A,\delta_A,1/2)$. The application of…
Large spin systems can exhibit unconventional types of magnetic ordering different from the ferromagnetic or N\'eel-like antiferromagnetic order commonly found in spin 1/2 systems. Spin-nematic phases, for instance, do not break…
To elucidate the underlying nature of the hidden order (HO) state in heavy-fermion compound URu2Si2, we measure electrical transport properties of ultraclean crystals in a high field/low temperature regime. Unlike previous studies, the…
On the basis of group theory and the first-principles calculations, we investigate high-rank multipole orderings in URu2Si2, which have been proposed as a genuine primary order parameter in the hidden order phase below 17.5K. We apply…
Within the framework of the Kondo-Heisenberg model, we analyse the effect of charge fluctuation on the modulated spin liquid (MSL) and antiferromagnetic (AF) orders which were established in a previous publication. We discuss the emergence…
We develop a Landau Ginzburg theory of the hidden order phase and the local moment antiferromagnetic phase of URu_2Si_2. We unify the two broken symmetries in a common complex order parameter and derive many experimentally relevant…
Despite several decades of both experimental and theoretical work the nature of the hidden order transition at THO = 17.5 K in URu2Si2 remains enigmatic. We report here low field DC magnetization as well as AC susceptibility measurements…
Since the 1985 discovery of the phase transition at $T_{\rm HO}=17.5$ K in the heavy-fermion metal URu$_2$Si$_2$, neither symmetry change in the crystal structure nor magnetic ordering have been observed, which makes this "hidden order"…
Layered 5$d$ transition iridium oxides, Sr$_2$(Ir,Rh)O$_4$, are described as unconventional Mott insulators with strong spin-orbit coupling. The undoped compound, Sr$_2$IrO$_4$, is a nearly ideal two-dimensional pseudospin-$1/2$ Heisenberg…
The heavy fermion metal CeB6 exhibits hidden order of antiferroquadrupolar (AFQ) type below T_Q=3.2K and subsequent antiferromagnetic (AFM) order at T_N=2.3K. It was interpreted as ordering of the quadrupole and dipole moments of a…
Measurements of the differential elastoresistance of URu$_2$Si$_2$ reveal that the fluctuations associated with the 17 K Hidden Order phase transition have a nematic component. Approaching the "Hidden Order" phase transition from above, the…