Spatial and Temporal Correlations of XY Macro Spins

Journal Article · 24 September 2018 · Nano Letters

DOI: https://doi.org/10.1021/acs.nanolett.8b01789 · OSTI ID:1473704

Streubel, Robert  ^[1]; Kent, Noah ^[2]; Dhuey, Scott ^[3]; Scholl, Andreas ^[4]; Kevan, Steve ^[5]; Fischer, Peter ^[2]

---

1. Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States). Materials Sciences Division
2. Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States). Materials Sciences Division; Univ. of California, Santa Cruz, CA (United States). Dept. of Physics
3. Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States). Molecular Foundry
4. Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States). Advanced Light Source (ALS)
5. Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States). Advanced Light Source (ALS); Univ. of Oregon, Eugene, OR (United States). Dept. of Physics

Here, we use nano disk arrays with square and honeycomb symmetry to investigate magnetic phases and spin correlations of XY dipolar systems at the micro scale. Utilizing magnetization sensitive x-ray photoemission electron microscopy, we probe magnetic ground states and the ”order-by-disorder” phenomenon predicted 30 years ago. We observe the antiferromagnetic striped ground state in square lattices, and six-fold symmetric structures, including trigonal vortex lattices and disordered floating vortices, in the honeycomb lattice. The spin frustration in the honeycomb lattice causes a phase transition from a long-range ordered locked phase over a floating phase with quasi long-range order and indications of a Berezinskii-Thouless-Kosterlitz-like character, to the thermally excited paramagnetic state. Absent spatial correlation and quasi periodic switching of isolated vortices in the quasi long-range ordered phase suggest a degeneracy of the vortex circulation.

• Research Organization: Lawrence Berkeley National Laboratory (LBNL), Berkeley, CA (United States)
• Sponsoring Organization: USDOE Office of Science (SC), Basic Energy Sciences (BES) (SC-22). Materials Sciences & Engineering Division; USDOE Office of Science (SC), Basic Energy Sciences (BES). Scientific User Facilities Division
• Grant/Contract Number: AC02-05CH11231
• OSTI ID: 1473704
• Alternate ID(s): OSTI ID: 1530322
• Journal Information: Nano Letters, Vol. 18, Issue 12; ISSN 1530-6984
• Publisher: American Chemical SocietyCopyright Statement
• Country of Publication: United States
• Language: English