Fig. 1: Kitaev paramagnetism and demagnetization cooling.
From: Magnetocaloric effect of topological excitations in Kitaev magnets
a Illustration of the Y-type cylindrical lattice and the topological excitations in the Kitaev model, where blue, green, and red bonds indicate respectively the x-, y-, and z-type interactions. The “+” (“−”) sign on the red bonds denote Dr = +1 (−1). A pair of π-fluxes (topological defects) can be created by changing the sign of Dr on a vertical bond (or an odd number of bonds). b The landscape of isentropes for the FM Kitaev model with field B up to 0.8. At zero field, the specific heat Cm curve shows a double-peak feature at TL ≃ 0.017 and TH ≃ 0.36, as shown in the inset. Two typical, and distinct ADR processes from the initial Ti1(2) to the final Tf1(2), are indicated with the white lines. c High-temperature isentropes following the Curie-Weiss behaviors and d low-temperature isentropes intersecting at the origin indicative of the emergent Curie paramagnetism. e The Grüneisen parameter ΓB at various low temperatures, which follows a ΓB ~ 1/B behavior as shown in the inset. f The magnetic susceptibility χm at various fields for the FM Kitaev model. The Curie-Weiss fitting at high (T ≳ TH) and Curie-law fitting at intermediate temperature (TL ≲ T ≲ TH) are indicated by the black and red dashed curves, respectively. g The comparison of the ADR processes with and without the pinning field BP = 0.1, and h shows the thermal entropy curves at field B =0 and 0.8. Starting from Ti2 at B = 0.8, the temperature can be decreased to Tf2 and \({T}_{{{{\rm{f}}}}2{\prime} }\) in the absence and under a pinning field BP = 0.1, respectively. The former is clearly lower than the latter, as highlighted by the shaded regions in both g, h. Source data are provided as a Source Data file.
