| Title: |
Multiple Magnetic Bilayers and Unconventional Criticality without Frustration in BaCuSi$_2$O$_6$ |
| Authors: |
Allenspach, S., Biffin, A., Stuhr, U., Tucker, G. S., Ohira-Kawamura, S., Kofu, M., Voneshen, D. J., Boehm, M., Normand, B., Laflorencie, N., Mila, F., Rüegg, Ch. |
| Source: |
Phys. Rev. Lett. 124, 177205 (2020) |
| Publication Year: |
2019 |
| Collection: |
Condensed Matter |
| Subject Terms: |
Condensed Matter - Strongly Correlated Electrons |
| More Details: |
The dimerized quantum magnet BaCuSi$_2$O$_6$ was proposed as an example of "dimensional reduction" arising near the magnetic-field-induced quantum critical point (QCP) due to perfect geometrical frustration of its inter-bilayer interactions. We demonstrate by high-resolution neutron spectroscopy experiments that the effective intra-bilayer interactions are ferromagnetic, thereby excluding frustration. We explain the apparent dimensional reduction by establishing the presence of three magnetically inequivalent bilayers, with ratios 3:2:1, whose differing interaction parameters create an extra field-temperature scaling regime near the QCP with a non-trivial but non-universal exponent. We demonstrate by detailed quantum Monte Carlo simulations that the magnetic interaction parameters we deduce can account for all the measured properties of BaCuSi$_2$O$_6$, opening the way to a quantitative understanding of non-universal scaling in any modulated layered system.
Comment: 14 pages, 9 figures |
| Document Type: |
Working Paper |
| DOI: |
10.1103/PhysRevLett.124.177205 |
| Access URL: |
http://arxiv.org/abs/1911.04161 |
| Accession Number: |
edsarx.1911.04161 |
| Database: |
arXiv |
