Unconventional field-induced spin gap in an S=1/2 Chiral staggered chain
| Autor: | Liu, J, Kittaka, S, Johnson, RD, Lancaster, T, Singleton, J, Sakakibara, T, Kohama, Y, Van Tol, J, Ardavan, A, Williams, BH, Blundell, SJ, Manson, ZE, Manson, JL, Goddard, PA |
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| Jazyk: | angličtina |
| Rok vydání: | 2019 |
| Předmět: | |
| Zdroj: | Physical review letters, 2019, Vol.122(5), pp.057207 [Peer Reviewed Journal] |
| ISSN: | 0031-9007 |
| Popis: | We investigate the low-temperature magnetic properties of the molecule-based chiral spin chain [Cu(pym)(H$_2$O)$_4$]SiF$_6\cdot$H$_2$O (pym = pyrimidine). Electron-spin resonance, magnetometry and heat capacity measurements reveal the presence of staggered $g$ tensors, a rich low-temperature excitation spectrum, a staggered susceptibility and a spin gap that opens on the application of a magnetic field. These phenomena are reminiscent of those previously observed in non-chiral staggered chains, which are explicable within the sine-Gordon quantum-field theory. In the present case, however, although the sine-Gordon model accounts well for the form of the temperature-dependence of the heat capacity, the size of the gap and its measured linear field dependence do not fit with the sine-Gordon theory as it stands. We propose that the differences arise due to additional terms in the Hamiltonian resulting from the chiral structure of [Cu(pym)(H$_2$O)$_4$]SiF$_6\cdot$H$_2$O, particularly a uniform Dzyaloshinskii-Moriya coupling and a four-fold periodic staggered field. Comment: 6 pages, 3 figures and supplemental information |
| Databáze: | OpenAIRE |
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