Spin delta-chain with competing exchange interactions
Background. Low-dimensional quantum magnets based on geometrically frustrated lattices are of considerable interest last time. As a typical example of such systems is the delta-chain which is a linear chain of triangles with spins on vertices. The delta-chain with AF exchange interactions is well st...
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Penza State University Publishing House
2025-03-01
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| Series: | Известия высших учебных заведений. Поволжский регион: Физико-математические науки |
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| author | V.Ya. Krivnov D.V. Dmitriev |
| author_facet | V.Ya. Krivnov D.V. Dmitriev |
| author_sort | V.Ya. Krivnov |
| collection | DOAJ |
| description | Background. Low-dimensional quantum magnets based on geometrically frustrated lattices are of considerable interest last time. As a typical example of such systems is the delta-chain which is a linear chain of triangles with spins on vertices. The delta-chain with AF exchange interactions is well studied and has a number of unusual properties. However, the same model with competing ferro (F)-and antiferromagnetic (AF) interactions is less studied. The purpose of this work is the study of the anisotropic F-AF delta-chain on the critical line separating different ground state phases, the calculation of the ground state degeneracy, residual entropy etc. Materials and methods. The study of this model is both analytically and numerically. It is proposed a method of construction of exact ground state wave functions and accounting of the number of ground ststes states in each spin sector. The analytical results are confirmed by numerical calculations of finite chains. Results. It is shown that the ground state manifold of the F-AF delta-chain on the critical line consists of localized magnons. Together with isolated magnons there are bound magnon complexes which give dominated contribution in ground state manifold in the thermodynamic limit. Conclusions. Spin systems with macroscopically degenerated ground state and with residual entropy demonstrate significant magnetocaloric effect. Taking into account great progress in a synthesis of frustrated magnets, it can be expected that real compounds of the FAF delta-chain type with parameters close to critical ones will be obtained and these compounds will be used for the construction of effective magnetocooling devices. |
| format | Article |
| id | doaj-art-2cffefeed45c4edc8f050b32187517ff |
| institution | OA Journals |
| issn | 2072-3040 |
| language | English |
| publishDate | 2025-03-01 |
| publisher | Penza State University Publishing House |
| record_format | Article |
| series | Известия высших учебных заведений. Поволжский регион: Физико-математические науки |
| spelling | doaj-art-2cffefeed45c4edc8f050b32187517ff2025-08-20T02:35:57ZengPenza State University Publishing HouseИзвестия высших учебных заведений. Поволжский регион: Физико-математические науки2072-30402025-03-01410.21685/2072-3040-2024-4-11Spin delta-chain with competing exchange interactions V.Ya. Krivnov0D.V. Dmitriev1Institute of Biochemical Physics named after N.M. Emanuel of the Russian Academy of Sciences, MoscowInstitute of Biochemical Physics named after N.M. Emanuel of the Russian Academy of Sciences, MoscowBackground. Low-dimensional quantum magnets based on geometrically frustrated lattices are of considerable interest last time. As a typical example of such systems is the delta-chain which is a linear chain of triangles with spins on vertices. The delta-chain with AF exchange interactions is well studied and has a number of unusual properties. However, the same model with competing ferro (F)-and antiferromagnetic (AF) interactions is less studied. The purpose of this work is the study of the anisotropic F-AF delta-chain on the critical line separating different ground state phases, the calculation of the ground state degeneracy, residual entropy etc. Materials and methods. The study of this model is both analytically and numerically. It is proposed a method of construction of exact ground state wave functions and accounting of the number of ground ststes states in each spin sector. The analytical results are confirmed by numerical calculations of finite chains. Results. It is shown that the ground state manifold of the F-AF delta-chain on the critical line consists of localized magnons. Together with isolated magnons there are bound magnon complexes which give dominated contribution in ground state manifold in the thermodynamic limit. Conclusions. Spin systems with macroscopically degenerated ground state and with residual entropy demonstrate significant magnetocaloric effect. Taking into account great progress in a synthesis of frustrated magnets, it can be expected that real compounds of the FAF delta-chain type with parameters close to critical ones will be obtained and these compounds will be used for the construction of effective magnetocooling devices. quantum magnetsfrustrationmagnonsmacroscopic degeneracy |
| spellingShingle | V.Ya. Krivnov D.V. Dmitriev Spin delta-chain with competing exchange interactions Известия высших учебных заведений. Поволжский регион: Физико-математические науки quantum magnets frustration magnons macroscopic degeneracy |
| title | Spin delta-chain with competing exchange interactions |
| title_full | Spin delta-chain with competing exchange interactions |
| title_fullStr | Spin delta-chain with competing exchange interactions |
| title_full_unstemmed | Spin delta-chain with competing exchange interactions |
| title_short | Spin delta-chain with competing exchange interactions |
| title_sort | spin delta chain with competing exchange interactions |
| topic | quantum magnets frustration magnons macroscopic degeneracy |
| work_keys_str_mv | AT vyakrivnov spindeltachainwithcompetingexchangeinteractions AT dvdmitriev spindeltachainwithcompetingexchangeinteractions |