Hilker, Timon

Date:   Thursday, August 2, 2018
Time:   11:00
Place:   ETH Zurich, Hönggerberg, HPF G 6
Hosts:   Michael Messer / Tilman Esslinger

Spin-resolved microscopy of doped Hubbard systems

Timon Hilker
University of Cambridge, UK

The doping of an antiferromagnet can lead to complex physics related to high-temperature superconductivity. In one dimension, however, the relevant competition between spin and density sectors is largely absent due to the separation of spin and density modes at low energy. With a quantum gas microscope for ultracold fermionic Li-6 in an optical lattice, we can study such systems with a unique control over kinetic energy, interactions and doping.

I will start by presenting our direct, single-spin resolved detection of antiferromagnetic correlations in spin-1/2 Hubbard chains [1]. Upon doping, the order decreases and their periodicity becomes incommensurate when measured with a standard two-point correlator [2]. With our full access to the spin and density distribution, we can directly measure three-point spin-hole-spin correlations and thus confirm that a hole in 1d only acts as a domain boundary of the spin-sector [3]. This is a direct consequence of the phenomenon of spin-charge separation and it allows to reveal the full correlations with non-local string operators [4].

Extending these techniques into the 2d regime, we study the effect of individual holes and doublons on an antiferromagnetic background. Without spin-charge separation, we find a significant reduction of the spin order around these mobile impurities, which is a first step towards the pairing of holes which might lead to d-wave superconductivity.

References
1. M. Boll et al., Science 353, 1257–1260 (2016)
2. G. Salomon et al. ArXiv 1803.08892 (2018)
3. T. A. Hilker et al., Science 357, 484-487 (2017)
4. M. Den Nijs & K. Rommelse Phys. Rev. B 40, 4709–4734 (1989)