相关论文: Octupole Moment as a Hidden Order Parameter in Orb…
An octupole ordering model is studied by the mean field theory, and its relevance to the phase IV of CexLa1-xB6 is discussed. The observed lattice distortion along the [111] direction is interpreted in terms of the \Gamma_{5g}-type…
We investigate effects of multipole moments in f-electron systems both from phenomenological and microscopic viewpoints. First, we discuss significant effects of octupole moment on the magnetic susceptibility in a paramagnetic phase. It is…
Motivated by the recent development in strong spin-orbit-coupled materials, we consider the dipole-octupole doublets on the triangular lattice. We propose the most general interaction between these unusual local moments. Due to the…
We study f-electron lattice models which are capable of supporting octupolar, as well dipolar and quadrupolar, order. Analyzing the properties of the Gamma8 ground state quartet, we find that (111)-type combinations of the Gamma5 octupoles…
The origin of non-collinear magnetism under quadrupolar ordering is investigated with CeB6 taken as a target system. The mode-mixing effect among 15 multipoles is analyzed based on the Ginzburg-Landau free energy. Then the lower magnetic…
d- and f-shells support a large number of local degrees of freedom: dipoles, quadrupoles, octupoles, hexadecapoles, etc. Usually, the ordering of any multipole component leaves the system sufficiently symmetrical to allow a second symmetry…
We show that time-reversal symmetry broken, centrosymmetric antiferromagnets with nonrelativistic spin-splitting are conveniently described in terms of the ferroic ordering of magnetic octupoles. The magnetic octupoles are the lowest-order…
Possible order parameters of the phase IV in CexLa1-xB6 are discussed with special attention to the lattice distortion recently observed. A \Gamma_{5u}-type octupole order with finite wave number is proposed as the origin of the distortion…
We present a theory for the relaxation time of the octupole order parameter in nanoscale chiral antiferromagnets (AFMs) coupled to thermal baths and spin injection sources. Using stochastic spin dynamics simulations, we demonstrate that the…
We introduce a mechanism in which coupling between fluctuating spin magnetic dipole moments and polar optical phonons leads to a non-zero ferroic ordering of quasi-static magnetoelectric multipoles. Using first-principles calculations…
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…
In many materials, ordered phases and their order parameters are easily characterized by standard experimental methods. "Hidden order" refers to a phase transition in which an ordered state emerges without such an easily detectable order…
In heavy fermion systems, multipole degrees of freedom make possible the emergence of rich phenomena, such as hidden orders and superconductivities. However, many of them remain unsolved since the origin of higher-rank multipole interaction…
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…
Broken symmetries in solids involving higher order multipolar degrees of freedom are historically referred to as "hidden orders" due to the formidable task of detecting them with conventional probes. Examples of such hidden orders include…
Motivated by experimental and theoretical interest in realizing multipolar orders in $d$-orbital materials, we discuss the quantum magnetism of $J\!=\!2$ ions which can be realized in spin-orbit coupled oxides with $5d^2$ transition metal…
The origin of octupole deformation for even-even nuclei near the doubly-closed shell configurations are investigated by means of the semiclassical periodic orbit theory. In order to focus on the change of shell structure due to deformation,…
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…
Magnetic multipoles have been recognized as order parameters characterizing magnetic structure in solids. Recently, magnetic octupoles have been proposed as the order parameters of time-reversal-symmetry breaking centrosymmetric…
The correlated motion of electrons in the presence of strong orbital fluctuations and correlations is investigated with respect to magnetic couplings and excitations in an orbitally degenerate ferromagnet. Introduction of the orbital degree…