Publication Type:

Journal Article

Source:

Physical Review B - Condensed Matter and Materials Physics, Volume 87, Number 21 (2013)

URL:

http://www.scopus.com/inward/record.url?eid=2-s2.0-84879991695&partnerID=40&md5=80547b252f5b36d01ddf6d8003448acb

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. © 2013 American Physical Society.

Notes:

cited By 4

Cite this Research Publication

R. Nath, Tsirlin, A. A., Khuntia, P., Janson, O., Förster, T., M. Padmanabhan, Li, J., Skourski, Y., Baenitz, M., Rosner, H., and Rousochatzakis, I., “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, 2013.