SU(4)-symmetric quantum spin-orbital liquids on various lattices
Masahiko Yamada, Masaki Oshikawa, George Jackeli
Abstract
An emergent <a:math xmlns:a="http://www.w3.org/1998/Math/MathML"><a:mrow><a:mi>SU</a:mi><a:mo>(</a:mo><a:mn>4</a:mn><a:mo>)</a:mo></a:mrow></a:math> symmetry discovered in the microscopic model for <b:math xmlns:b="http://www.w3.org/1998/Math/MathML"><b:msup><b:mi>d</b:mi><b:mn>1</b:mn></b:msup></b:math> honeycomb materials [M. G. Yamada, M. Oshikawa, and G. Jackeli, ] has enabled us to tailor exotic <c:math xmlns:c="http://www.w3.org/1998/Math/MathML"><c:mrow><c:mi>SU</c:mi><c:mo>(</c:mo><c:mn>4</c:mn><c:mo>)</c:mo></c:mrow></c:math> models in real materials. In the honeycomb structure, the emergent <d:math xmlns:d="http://www.w3.org/1998/Math/MathML"><d:mrow><d:mi>SU</d:mi><d:mo>(</d:mo><d:mn>4</d:mn><d:mo>)</d:mo></d:mrow></d:math> Heisenberg model would potentially have a quantum spin-orbital liquid ground state due to the , and we can also expect similar spin-orbital liquids in three-dimensional versions of the honeycomb lattice. In such quantum spin-orbital liquids, both the spin and orbital degrees of freedom become fractionalized and entangled together due to the strong frustrated interactions between them. Similarly to spinons in pure quantum spin liquids, quantum spin-orbital liquids can host not only spinon excitations, but also fermionic excitations at low temperature.