Ae. Jacobs et al., THEORY OF MAGNETIC-STRUCTURES OF CSCUCL3 IN TRANSVERSE MAGNETIC-FIELD, Journal of the Physical Society of Japan, 62(11), 1993, pp. 4066-4080
At zero field CsCuCl3 is known to form a helical spin structure along
the c-axis and the 120-degrees structure in the c-plane. This paper di
scusses theoretically the effect of a magnetic field applied perpendic
ular to the c-axis, which breaks the axial symmetry. First the classic
al ground state is studied. The transverse magnetic field deforms the
helical spin structure and causes a continuous phase transition from t
he helical (i.e. incommensurate) spin structure to a commensurate stat
e, as the field increases. Detailed studies are made of the helix pitc
h and of the nature of the inconunensurate spin structure as functions
of the field. The commensurate state has a nontrivial degeneracy, whi
ch is lifted by quantum (and thermal) fluctuations. Therefore the 1/S
expansion is applied to determine the spin structure of the commensura
te state. From these studies possible spin structures are suggested fo
r each region of field strength.