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Resonant torsion magnetometry in anisotropic quantum materials

Cornell Affiliated Author(s)


K. Modic
Maja Bachmann
B. Ramshaw
Frank Arnold
K. Shirer
Amelia Estry
Jon Betts
Nirmal Ghimire
E. Bauer
Marcus Schmidt
Michael Baenitz
E. Svanidze
Ross McDonald
Arkady Shekhter
Philip Moll


Unusual behavior in quantum materials commonly arises from their effective low-dimensional physics, reflecting the underlying anisotropy in the spin and charge degrees of freedom. Here we introduce the magnetotropic coefficient k = ∂2F/∂θ2, the second derivative of the free energy F with respect to the magnetic field orientation θ in the crystal. We show that the magnetotropic coefficient can be quantitatively determined from a shift in the resonant frequency of a commercially available atomic force microscopy cantilever under magnetic field. This detection method enables part per 100 million sensitivity and the ability to measure magnetic anisotropy in nanogram-scale samples, as demonstrated on the Weyl semimetal NbP. Measurement of the magnetotropic coefficient in the spin-liquid candidate RuCl3 highlights its sensitivity to anisotropic phase transitions and allows a quantitative comparison to other thermodynamic coefficients via the Ehrenfest relations. © 2018, The Author(s).

Date Published


Nature Communications








Group (Lab)

Brad Ramshaw Group

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