Related papers: Hidden and antiferromagnetic order as a rank-5 sup…
Novel electronic states resulting from entangled spin and orbital degrees of freedom are hallmarks of strongly correlated f-electron systems. A spectacular example is the so-called 'hidden-order' phase transition in the heavy-electron metal…
The conventional order parameters in quantum matters are often characterized by 'spontaneous' broken symmetries. However, sometimes the broken symmetries may blend with the invariant symmetries to lead to mysterious emergent phases. The…
URu2Si2 is one of the most enigmatic strongly-correlated-electron systems and offers a fertile testing ground for new concepts in condensed matter science. In spite of >30 years of intense research, no consensus on the order parameter of…
We argue that key characteristics of the enigmatic transition at $T_0= 17.5K $ in $URu_2Si_2$ indicate that the hidden order is a density wave formed within a band of composite quasiparticles, whose detailed structure is determined by local…
The hidden order developing below 17.5K in the heavy fermion material URu2Si2 has eluded identification for over twenty five years. This paper will review the recent theory of ``hastatic order,'' a novel two-component order parameter…
We discuss the discovery of pressure-induced antiferromagnetism in URu_2Si_2, in the context of neutron, NMR and \mu SR results. The identification of a critical pressure separating mean-field and Ising phase transitions leads us to propose…
The development of collective long-range order via phase transitions occurs by the spontaneous breaking of fundamental symmetries. Magnetism is a consequence of broken time-reversal symmetry while superfluidity results from broken gauge…
We study URu$_{2-x}$Fe$_x$Si$_2$, in which two types of staggered phases compete at low temperature as the iron concentration $x$ is varied: the nonmagnetic "hidden order" (HO) phase below the critical concentration $x_c$, and…
It is shown that the hidden ordered (HO) state in heavy fermionic metal URu2Si2 is either nonconventional charge density wave (CDW) or antiferroelectric (AFE) commensurate ordering. Similar to antiferromagnetic (AF) order an…
The heavy fermion intermetallic compound URu2Si2 exhibits a "hidden-order" phase below the temperature of 17.5 K, which supports both anomalous metallic behavior and unconventional superconductivity. While these individual phenomena have…
An unconventional pairing mechanism in the heavy-fermion material $\mathrm{URu_{2}Si_{2}}$ is studied. We propose a mixed singlet-triplet $d$-density wave to be the hidden-order state in $\mathrm{URu_{2}Si_{2}}$. The exotic order is…
The heavy-fermion compound URu2Si2 exhibits a hidden-order phase below the temperature, ~ 17.5 K. In spite of intense research for past three decades, no consensus on the order parameter exists and the nature has posed a long-standing…
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…
The hidden order phase of URu$_2$Si$_2$ has eluded identification for over thirty-five years. A compelling proposal that explains the Ising heavy-fermion nature of the material is \emph{hastatic order}: a symmetry breaking heavy-Fermi…
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…
The behavior of the so-called weak moment antiferromagnetic states, observed in the heavy-fermion superconductors UPt$_3$ and URu$_2$Si$_2$, is discussed in view of recent $\mu$SR results obtained as function of control parameters like…
When matter is cooled from high temperatures, collective instabilities develop amongst its constituent particles that lead to new kinds of order. An anomaly in the specific heat is a classic signature of this phenomenon. Usually the…
We have investigated the nature of the competition between hidden order and antiferromagnetic (AF) order in URu_2Si_2 by performing the neutron scattering experiments under hydrostatic-pressure P, uniaxial-stress sigma, and Rh-substitution…
Shubnikov-de Haas measurements of high quality URu2Si2 single crystals reveal two previously unobserved Fermi surface branches in the so-called hidden order phase. Therefore about 55% of the enhanced mass is now detected. Under pressure in…
URu$_2$Si$_2$ is surely one of the most mysterious of the heavy-fermion compounds. Despite more than twenty years of experimental and theoretical works, the order parameter of the transition at $T_0 = 17.5$ K is still unknown. The state…