No evidence for orbital loop currents in charge-ordered YBa2Cu3O6+x from polarized neutron diffraction
| Autor: | Stephen M Hayden, Doug Bonn, J. Kulda, Elizabeth Blackburn, T. P. Croft, Walter Hardy, Ruixing Liang |
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| Rok vydání: | 2017 |
| Předmět: |
Superconductivity
Physics Condensed matter physics Neutron diffraction 02 engineering and technology Muon spin spectroscopy 021001 nanoscience & nanotechnology 01 natural sciences Upper and lower bounds Loop (topology) Nuclear magnetic resonance Condensed Matter::Superconductivity 0103 physical sciences Condensed Matter::Strongly Correlated Electrons Cuprate Neutron 010306 general physics 0210 nano-technology Pseudogap |
| Zdroj: | Physical Review B. 96 |
| ISSN: | 2469-9969 2469-9950 |
| DOI: | 10.1103/physrevb.96.214504 |
| Popis: | It has been proposed that the pseudogap state of underdoped cuprate superconductors may be due to a transition to a phase which has circulating currents within each unit cell. Here, we use polarized neutron diffraction to search for the corresponding orbital moments in two samples of underdoped YBa$_2$Cu$_3$O$_{6+x}$ with doping levels $p=0.104$ and 0.123. In contrast to some other reports using polarized neutrons, but in agreement with nuclear magnetic resonance and muon spin rotation measurements, we find no evidence for the appearance of magnetic order below 300 K. Thus, our experiment suggests that such order is not an intrinsic property of high-quality cuprate superconductor single crystals. Our results provide an upper bound for a possible orbital loop moment which depends on the pattern of currents within the unit cell. For example, for the CC-$\theta_{II}$ pattern proposed by Varma, we find that the ordered moment per current loop is less than 0.013 $\mu_B$ for $p=0.104$. |
| Databáze: | OpenAIRE |
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