"Spin molecular-orbital coupling", Ben Powell (university of Queensland)

• Speaker: Prof. Ben Powell, University of Queensland
• Title: "Spin molecular-orbital coupling"
• Date: Thursday, 21st September
• Time: 15:00-16:00
• Venue: C209, Center Building

Spin molecular-orbital coupling

Spin orbit coupling (SOC) is, perhaps, most familiar from atomic physics, where the electron’s spin becomes entangled with its orbital angular momentum. In molecular systems the electronic spin can also couple to currents running around the molecule [1]. This “spin molecular-orbital coupling” (SMOC) is not simply a projection of the atom SOC, but a new effect that emerges at the molecular scale. The simplest example of SMOC is cyclic molecules, e.g., polygons with only an N-fold rotational symmetry. If N is odd the SMOC term in the Hamiltonian looks like an intrinsically anisotropic form of the atomic SOC (λL.S, where L is the molecular-orbital angular momentum) with a ‘ladder’ of states coupled by SMOC. But, if N is even the orbital and total angular momenta are essentially periodic and SMOC leads to umklapp like events in angular momentum. In this talk I will introduce these ideas more fully and then discuss SMOC in real material systems [2] and the implications for magnetic phases when both SMOC and electronic correlations are strong [3].

[1] A. L. Khosla, A. C. Jacko, J. Merino, and B. J. Powell, Phys. Rev. B 95, 115109 (2017)

[2] A. C. Jacko, A. L. Khosla, J. Merino, and B. J. Powell, Phys. Rev. B 95, 155120 (2017)

[3] J. Merino, A. C. Jacko, A. L. Khosla, and B. J. Powell, Phys. Rev. B 94, 205109 (2016).