Spin dynamics of S = 1/2 Heisenberg chains with a staggered transverse field: electron spin resonance studies (Review Article)

• Дата: 2012
• Автор: Zvyagin, S.A.
• Формат: Стаття
• Мова: English
• Опубліковано: Фізико-технічний інститут низьких температур ім. Б.І. Вєркіна НАН України 2012
• Назва видання: Физика низких температур
• Теми: К 80-летию Виктора Валентиновича Еременко
• Онлайн доступ: https://nasplib.isofts.kiev.ua/handle/123456789/117611
• Назва журналу: Digital Library of Periodicals of National Academy of Sciences of Ukraine
• Цитувати: Spin dynamics of S = 1/2 Heisenberg chains with a staggered transverse field: electron spin resonance studies (Review Article) / S.A. Zvyagin // Физика низких температур. — 2012. — Т. 38, № 9. — С. 1032–1040. — Бібліогр.: 37 назв. — англ.

In this article I review recent achievements on experimental studies of magnetic excitations in the copper pyrimidine dinitrate [PM–Cu(NO₃ )₂ (H ₂O) ₂ ]n (PM = pyrimidine), an S = 1/2 antiferromagnetic chain material with alternating g-tensor and the Dzyaloshinskii–Moriya interaction, by means of high-field electron spin resonance (ESR). Due to this alternation, in the 1D critical regime this material exhibits a field-induced gap. The excitation spectrum is formed by solitons and their bound states, breathers, and can be effectively described using the sine-Gordon model. With increasing temperature, the soliton-breather regime can be suppressed, resulting in a substantial evolution of ESR parameters. These changes can be described using a new theoretical concept recently proposed for S =1/2 AF chains with a staggered transverse field. High magnetic field induces a transition into spin-polarized state with the excitation spectrum formed by magnons. Nonmonotonous behavior of the field-induced gap is observed in the vicinity of saturation field. The experimental data are compared with results of existing theoretical approaches, revealing an excellent agreement with the predictions.