Speaker
Description
Recent experiments on artificial spin systems with continuous degrees of freedom [1,2] have renewed the interest of classical dipoles on regular lattices. The pioneering work of Luttinger-Tisza [3] paved the way to construct the ground state of such systems. Remarkably, in many different two- or three-dimensional geometries, dipolar spin systems show a continuous ground state degeneracy [4]. Since the degeneracies are accidental, order-by-disorder transitions are observed if the system is exposed to thermal fluctuations or disorder [5]. Here, we show how these phenomena can be traced to general properties of the lattice. Based on the properties of the point symmetry group of the lattices, we describe how the ground state degeneracy and the order-by-disorder transitions arise.
References:
[1] N. Leo et al., Nat. Comm. 9, 2850 (2018)
[2] R. Streubel et al., Nano Lett., acs.nanolett.8b01789 (2018).
[3] J. Luttinger and L. Tisza, Physical Review 70.954 (1946)
[4] P. I. Belobrov et al., Zh. Eksp. Teor. Fiz 84, 1097 (1983)
[5] S. Prakash and C. L. Henley, Phys. Rev. B 42, 6574 (1990)
