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Low temperature structural phase transition and incommensurate lattice modulation in the spin gap compound BaCuSi2O6

E. C. Samulon·Z. Islam·S. E. Sebastian·P. B. Brooks·M. K. McCourt Jr.·J. Ilavsky·I. R. Fisher
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Abstract

Results of high resolution x-ray diffraction experiments are presented for single crystals of the spin gap compound BaCuSi$_2$O$_6$ in the temperature range from 16 to 300 K. The data show clear evidence of a transition from the room temperature tetragonal phase into an incommensurately modulated orthorhombic structure below $\sim$100 K. This lattice modulation is characterized by a resolution limited wave vector {\bf q}$_{IC}$=(0,$\sim$0.13,0) and its 2$^{nd}$ and 3$^{rd}$ harmonics. The phase transition is first order and exhibits considerable hysteresis. This observation implies that the spin Hamiltonian representing the system is more complex than originally thought.

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E. C. Samulon, Z. Islam, S. E. Sebastian, P. B. Brooks, M. K. McCourt Jr., J. Ilavsky, I. R. Fisher. 2005-12-22. Low temperature structural phase transition and incommensurate lattice modulation in the spin gap compound BaCuSi2O6. https://doi.org/10.1103/physrevb.73.100407

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