Itinerant magnetic multipole moments of rank five as the hidden order in URu(2)Si(2).
A broken symmetry ground state without any magnetic moments has been calculated by means of the local-density approximation to density functional theory plus a local exchange term, the so-called LDA+U approach, for URu(2)Si(2). The solution is analyzed in terms of a multipole tensor expansion of the itinerant density matrix and is found to be a nontrivial magnetic multipole. Analysis and further calculations show that this type of multipole enters naturally in time reversal breaking in the presence of large effective spin-orbit coupling and coexists with magnetic moments for most magnetic actinides.
Department of Physics and Materials Science, Uppsala University, SE-75121 Uppsala, Sweden.
Francesco
F
Cricchio
Fredrik
F
Bultmark
Oscar
O
Grånäs
Lars
L
Nordström