  We have measured magnetic torque on a T${_N}$ = 7 K single crystal of
${\alpha}$-RuCl${_3}$ , as a function of the field angle in the ab-plane,
focusing on temperatures between 2 and 20 K and fields from 0 to 9 T. We find a
rich spectrum of signals, many of which can be classified by their angular
periodicity. The sample shows an oscillation with a period of 180$^{\circ}$
(i.e. two-fold periodicity) which we argue is due to residual strain within the
crystal, rather than being intrinsic. In addition, within the magnetically
ordered zigzag phase there is a 60$^{\circ}$ period (i.e. six-fold) sawtooth
pattern, which can be explained by reorientation of the zigzag domains as the
crystal rotates in the applied field. Suppressing the zigzag order with an
applied field above ${\sim}$ 8 T at low temperature, a six-fold sinusoidal
signal remains, suggesting that there is fluctuating zigzag order in the
putative field-induced quantum spin liquid state. Finally, our key finding is a
sharp, step-like feature that appears at low temperature for fields just above
the zigzag phase boundary, at the so-called B2-axes. This is similar to
theoretically predicted behaviour for a state with Ising topological order,
which is expected for a Kitaev spin liquid in an applied magnetic field.
