ScholarWorks@성균관대학교

초록

Despite exhibiting magnetic long-range order below TN = 26.7 K, the honeycomb cobaltate Na2Co2TeO6 is predicted to enter a Kitaev spin liquid state when subjected to small external perturbations. While most of the reported literature investigates the effects of magnetic fields applied parallel to the honeycomb layers, we present high-resolution capacitance dilatometry studies for fields perpendicular to the Co-planes up to 15 T. Gruneisen analysis reveals the effect of uniaxial out-of-plane strain and shows that antiferromagnetic order in Na2Co2TeO6 is stabilized at a rate of partial derivative T-N/partial derivative(p)c = 0.28(5) K/GPa. Further, failure of the Gruneisen scaling at low temperatures around T-cr similar or equal to 7.5 K demonstrates the presence of competing energy scales. In contrast to an only weak field dependence of the anomaly at TN, a broad hump at Tcr(B = 0 T) evolves into a sharp peak at high fields applied B parallel to c. Our magnetostriction data show that a kink in the magnetization at BC similar or equal to 4.6 T is accompanied by an inflection point in the field-induced length changes, which is likely related to weak unequal spin canting. All observed phenomena leave their signatures in the magnetoelastic phase diagram as constructed by our experimental results.

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