We theoretically investigate the dynamics of antiferromagnetic domain walls driven by spin-orbit torques in antiferromagnet-heavy-metal bilayers. We show that spin-orbit torques drive antiferromagnetic domain walls much faster than ferromagnetic domain walls. As the domain wall velocity approaches the maximum spin-wave group velocity, the domain wall undergoes Lorentz contraction and emits spin...

We investigate the ground states of classical Heisenberg spin systems which have point group symmetry. Examples are the regular polygons (spin rings) and the seven quasi-regular polyhedra including the five Platonic solids. For these examples, ground states with special properties, e. g. coplanarity or symmetry, can be completely enumerated using group-theoretical methods. For systems having co...

In metallic ferromagnets, the spin-transfer torque and spin-motive force are known to exhibit a reciprocal relationship. Recent experiments on ferromagnets with strong spin-orbit coupling have revealed a rich complexity in the interaction between itinerant charge carriers and magnetization, but a full understanding of this coupled dynamics is lacking. Here, we develop a general phenomenology of...

We give a construction of the spin representations of orthogonal groups over Z that are compact over R. Such an orthogonal group is associated to a positive definite, integral lattice L with good reduction at all primes. A representation of the group scheme Spin(L) is an even, unimodular lattice M of rank 2k, where k = n−1 if rank(L) = 2n is even and k = n if rank(L) = 2n + 1 is odd. To constru...

We discuss techniques of the density matrix renormalization group and their application to interacting fermion systems in more than one dimension. We show numerical results for equal–time spin–spin and singlet pair field correlation functions, as well as the spin gap for the Hubbard model on two chains. The system is a gapped spin liquid at half–filling and shows weak algebraic d-wave–like pair...

The left-right chiral and ferromagnetic-antiferromagnetic double-spin-glass clock model, with the crucially even number of states q=4 and in three dimensions d=3, has been studied by renormalization-group theory. We find, for the first time to our knowledge, four spin-glass phases, including conventional, chiral, and quadrupolar spin-glass phases, and phase transitions between spin-glass phases...

We study the problem of spin diffusion in magnetic systems without longrange order. We discuss the example of the 1D spin chain. For the system described by the Heisenberg Hamiltonian we show that there are no diffusive excitations. However, the addition of an arbitrarily small dissipation term, such as the spin-phonon interaction leads to diffusive excitations in the long time limit. For those...

Band structures of group-IV two-dimensional materials are studied by carrying out first-principles calculations including spin-orbit coupling (SOC). We propose a method that identifies irreducible representations (IR) bands using computers. identify IR for the planar and buckled discuss difference between obtained non-SOC SOC calculations. In particular, we clarify at Dirac point where split be...

The detailed selection rules for reactive collisions reported by Quack using molecular symmetry group are derived by using angular momentum algebra. Instead of the representations of the permutation–inversion group for both nuclear spin and rovibronic coordinate wavefunctions, those of the rotation group for nuclear spin wavefunction only are used. The method allows more straightforward derivat...

The Blume-Emery-Griffiths spin glass is studied by renormalization-group theory in d=3 . The boundary between the ferromagnetic and paramagnetic phases has first-order and two types of second-order segments. This topology includes an inverted tricritical point, first-order transitions replacing second-order transitions as temperature is lowered. The phase diagrams show disconnected spin-glass r...