Magnetization and spin dynamics of the spin S=12 hourglass nanomagnet Cu5(OH)2(NIPA)4·10H2O

R. Nath, A. A. Tsirlin, P. Khuntia, O. Janson, T. Förster, M. Padmanabhan, Jing Li, Yu Skourski, M. Baenitz, H. Rosner, I. Rousochatzakis

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Abstract

We report a combined experimental and theoretical study of the spin S=12 nanomagnet Cu5(OH)2(NIPA)4·10H 2O (Cu5-NIPA). Using thermodynamic, electron spin resonance, and 1H nuclear magnetic resonance measurements on one hand, and ab initio density-functional band-structure calculations, exact diagonalizations, and a strong-coupling theory on the other, we derive a microscopic magnetic model of Cu5-NIPA and characterize the spin dynamics of this system. The elementary fivefold Cu2+ unit features an hourglass structure of two corner-sharing scalene triangles related by inversion symmetry. Our microscopic Heisenberg model comprises one ferromagnetic and two antiferromagnetic exchange couplings in each triangle, stabilizing a single spin S=12 doublet ground state (GS), with an exactly vanishing zero-field splitting (by Kramers' theorem), and a very large excitation gap of Δ≠68 K. Thus, Cu5-NIPA is a good candidate for achieving long electronic spin relaxation (T1) and coherence (T2) times at low temperatures, in analogy to other nanomagnets with low-spin GS's. Of particular interest is the strongly inhomogeneous distribution of the GS magnetic moment over the five Cu2+ spins. This is a purely quantum-mechanical effect since, despite the nonfrustrated nature of the magnetic couplings, the GS is far from the classical collinear ferrimagnetic configuration. Finally, Cu5-NIPA is a rare example of a S=12 nanomagnet showing an enhancement in the nuclear spin-lattice relaxation rate 1/T1 at intermediate temperatures.

Original languageEnglish
Article number214417
JournalPhysical Review B - Condensed Matter and Materials Physics
Volume87
Issue number21
DOIs
Publication statusPublished - Jun 14 2013

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Spin dynamics
spin dynamics
Ground state
Magnetization
magnetization
Magnetic resonance measurement
Magnetic couplings
Exchange coupling
Spin-lattice relaxation
triangles
ground state
Magnetic moments
Band structure
Paramagnetic resonance
Nuclear magnetic resonance
Thermodynamics
Temperature
spin-lattice relaxation
nuclear spin
electron paramagnetic resonance

ASJC Scopus subject areas

  • Condensed Matter Physics
  • Electronic, Optical and Magnetic Materials

Cite this

Nath, R., Tsirlin, A. A., Khuntia, P., Janson, O., Förster, T., Padmanabhan, M., ... Rousochatzakis, I. (2013). Magnetization and spin dynamics of the spin S=12 hourglass nanomagnet Cu5(OH)2(NIPA)4·10H2O. Physical Review B - Condensed Matter and Materials Physics, 87(21), [214417]. https://doi.org/10.1103/PhysRevB.87.214417

Magnetization and spin dynamics of the spin S=12 hourglass nanomagnet Cu5(OH)2(NIPA)4·10H2O. / Nath, R.; Tsirlin, A. A.; Khuntia, P.; Janson, O.; Förster, T.; Padmanabhan, M.; Li, Jing; Skourski, Yu; Baenitz, M.; Rosner, H.; Rousochatzakis, I.

In: Physical Review B - Condensed Matter and Materials Physics, Vol. 87, No. 21, 214417, 14.06.2013.

Research output: Contribution to journalArticle

Nath, R, Tsirlin, AA, Khuntia, P, Janson, O, Förster, T, Padmanabhan, M, Li, J, Skourski, Y, Baenitz, M, Rosner, H & Rousochatzakis, I 2013, 'Magnetization and spin dynamics of the spin S=12 hourglass nanomagnet Cu5(OH)2(NIPA)4·10H2O', Physical Review B - Condensed Matter and Materials Physics, vol. 87, no. 21, 214417. https://doi.org/10.1103/PhysRevB.87.214417
Nath, R. ; Tsirlin, A. A. ; Khuntia, P. ; Janson, O. ; Förster, T. ; Padmanabhan, M. ; Li, Jing ; Skourski, Yu ; Baenitz, M. ; Rosner, H. ; Rousochatzakis, I. / Magnetization and spin dynamics of the spin S=12 hourglass nanomagnet Cu5(OH)2(NIPA)4·10H2O. In: Physical Review B - Condensed Matter and Materials Physics. 2013 ; Vol. 87, No. 21.
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abstract = "We report a combined experimental and theoretical study of the spin S=12 nanomagnet Cu5(OH)2(NIPA)4·10H 2O (Cu5-NIPA). Using thermodynamic, electron spin resonance, and 1H nuclear magnetic resonance measurements on one hand, and ab initio density-functional band-structure calculations, exact diagonalizations, and a strong-coupling theory on the other, we derive a microscopic magnetic model of Cu5-NIPA and characterize the spin dynamics of this system. The elementary fivefold Cu2+ unit features an hourglass structure of two corner-sharing scalene triangles related by inversion symmetry. Our microscopic Heisenberg model comprises one ferromagnetic and two antiferromagnetic exchange couplings in each triangle, stabilizing a single spin S=12 doublet ground state (GS), with an exactly vanishing zero-field splitting (by Kramers' theorem), and a very large excitation gap of Δ{\^a}‰ 68 K. Thus, Cu5-NIPA is a good candidate for achieving long electronic spin relaxation (T1) and coherence (T2) times at low temperatures, in analogy to other nanomagnets with low-spin GS's. Of particular interest is the strongly inhomogeneous distribution of the GS magnetic moment over the five Cu2+ spins. This is a purely quantum-mechanical effect since, despite the nonfrustrated nature of the magnetic couplings, the GS is far from the classical collinear ferrimagnetic configuration. Finally, Cu5-NIPA is a rare example of a S=12 nanomagnet showing an enhancement in the nuclear spin-lattice relaxation rate 1/T1 at intermediate temperatures.",
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N2 - We report a combined experimental and theoretical study of the spin S=12 nanomagnet Cu5(OH)2(NIPA)4·10H 2O (Cu5-NIPA). Using thermodynamic, electron spin resonance, and 1H nuclear magnetic resonance measurements on one hand, and ab initio density-functional band-structure calculations, exact diagonalizations, and a strong-coupling theory on the other, we derive a microscopic magnetic model of Cu5-NIPA and characterize the spin dynamics of this system. The elementary fivefold Cu2+ unit features an hourglass structure of two corner-sharing scalene triangles related by inversion symmetry. Our microscopic Heisenberg model comprises one ferromagnetic and two antiferromagnetic exchange couplings in each triangle, stabilizing a single spin S=12 doublet ground state (GS), with an exactly vanishing zero-field splitting (by Kramers' theorem), and a very large excitation gap of Δ≠68 K. Thus, Cu5-NIPA is a good candidate for achieving long electronic spin relaxation (T1) and coherence (T2) times at low temperatures, in analogy to other nanomagnets with low-spin GS's. Of particular interest is the strongly inhomogeneous distribution of the GS magnetic moment over the five Cu2+ spins. This is a purely quantum-mechanical effect since, despite the nonfrustrated nature of the magnetic couplings, the GS is far from the classical collinear ferrimagnetic configuration. Finally, Cu5-NIPA is a rare example of a S=12 nanomagnet showing an enhancement in the nuclear spin-lattice relaxation rate 1/T1 at intermediate temperatures.

AB - We report a combined experimental and theoretical study of the spin S=12 nanomagnet Cu5(OH)2(NIPA)4·10H 2O (Cu5-NIPA). Using thermodynamic, electron spin resonance, and 1H nuclear magnetic resonance measurements on one hand, and ab initio density-functional band-structure calculations, exact diagonalizations, and a strong-coupling theory on the other, we derive a microscopic magnetic model of Cu5-NIPA and characterize the spin dynamics of this system. The elementary fivefold Cu2+ unit features an hourglass structure of two corner-sharing scalene triangles related by inversion symmetry. Our microscopic Heisenberg model comprises one ferromagnetic and two antiferromagnetic exchange couplings in each triangle, stabilizing a single spin S=12 doublet ground state (GS), with an exactly vanishing zero-field splitting (by Kramers' theorem), and a very large excitation gap of Δ≠68 K. Thus, Cu5-NIPA is a good candidate for achieving long electronic spin relaxation (T1) and coherence (T2) times at low temperatures, in analogy to other nanomagnets with low-spin GS's. Of particular interest is the strongly inhomogeneous distribution of the GS magnetic moment over the five Cu2+ spins. This is a purely quantum-mechanical effect since, despite the nonfrustrated nature of the magnetic couplings, the GS is far from the classical collinear ferrimagnetic configuration. Finally, Cu5-NIPA is a rare example of a S=12 nanomagnet showing an enhancement in the nuclear spin-lattice relaxation rate 1/T1 at intermediate temperatures.

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