Phases of d-orbital bosons in optical lattices
2015 (English)In: New Journal of Physics, ISSN 1367-2630, Vol. 17, 053004Article in journal (Refereed) Published
We explore the properties of bosonic atoms loaded into the d bands of an isotropic square optical lattice. Following the recent experimental success reported in Zhai et al (2013 Phys. Rev. A 87 063638), in which populating d bands with a 99 fidelity was demonstrated, we present a theoretical study of the possible phases that can appear in this system. Using the Gutzwiller ansatz for the three d band orbitals we map the boundaries of the Mott insulating phases. For not too large occupation, two of the orbitals are predominantly occupied, while the third, of a slightly higher energy, remains almost unpopulated. In this regime, in the superfluid phase we find the formation of a vortex lattice, where the vortices come in vortex/anti-vortex pairs with two pairs locked to every site. Due to the orientation of the vortices time-reversal symmetry is spontaneously broken. This state also breaks a discrete -symmetry. We further derive an effective spin-1/2 model that describe the relevant physics of the lowest Mott-phase with unit filling. We argue that the corresponding two dimensional phase diagram should be rich with several different phases. We also explain how to generate anti-symmetric spin interactions that can give rise to novel effects like spin canting.
Place, publisher, year, edition, pages
2015. Vol. 17, 053004
cold atoms, optical lattice, phase diagram, spin model
IdentifiersURN: urn:nbn:se:kth:diva-170266DOI: 10.1088/1367-2630/17/5/053004ISI: 000355277100004ScopusID: 2-s2.0-84930007874OAI: oai:DiVA.org:kth-170266DiVA: diva2:831696
QC 201506302015-06-302015-06-292015-08-17Bibliographically approved