Inelastic neutron scattering studies on the odd-membered antiferromagnetic wheel Cr8Ni

Michael L. Baker; Oliver Waldmann; Stergios Piligkos; Roland Bircher; Olivier Cador; Stefano Carretta; David Collison; Felix Fernandez-Alonso; Eric J.L. McInnes; Hannu Mutka; Andrew Podlesnyak; Floriana Tuna; Stefan Ochsenbein; Roberta Sessoli; Andreas Sieber; Grigore A. Timco; Høgni Weihe; Hans U. Güdel; Richard E.P. Winpenny

doi:10.1103/PhysRevB.86.064405

Inelastic neutron scattering studies on the odd-membered antiferromagnetic wheel Cr₈Ni

Michael L. Baker, Oliver Waldmann, Stergios Piligkos, Roland Bircher, Olivier Cador, Stefano Carretta, David Collison, Felix Fernandez-Alonso, Eric J.L. McInnes, Hannu Mutka, Andrew Podlesnyak, Floriana Tuna, Stefan Ochsenbein, Roberta Sessoli, Andreas Sieber, Grigore A. Timco, Høgni Weihe, Hans U. Güdel, Richard E.P. Winpenny

Department of Chemistry

10 Citations (Scopus)

Abstract

[ ⁽iC ₃H ₇)2NH ₂][Cr ₈NiF ₉(O ₂CCMe)18], or Cr ₈Ni, is a prominent example of an odd-membered antiferromagnetic "wheel." A detailed characterization of the magnetic properties of Cr ₈Ni has been conducted. Inelastic neutron scattering (INS) is used to investigate the energy and momentum transfer dependence of the low-lying spin excitations, including excited states inaccessible by other experimental techniques. The richness of the INS data, in conjunction with microscopic spin Hamiltonian simulations, enables an accurate characterization of the magnetic properties of Cr ₈Ni. Nearest-neighbor exchange constants of J _CrCr = 1.31 meV and J _CrNi = 3.22 meV are determined, and clear evidence of axial single-ion anisotropy is found. The parameters determined by INS are shown to fit magnetic susceptibility. The spectroscopic identification of several successive S=1 excited total spin states and lowest spin band excitations show that the rotational band picture, valid for bipartite AFM wheels, breaks down for this odd-numbered wheel. The exchange constants determined here differ from previous efforts based on bulk measurements, and possible reasons are discussed. The large J _CrNi/J _CrCr ratio in Cr ₈Ni puts this wheel into a regime with strong quantum fluctuations in which the ground state can be described with a valence bond solid state picture.

Original language	English
Article number	064405
Journal	Physical Review B Condensed Matter
Volume	86
Issue number	6
Number of pages	11
ISSN	0163-1829
DOIs	https://doi.org/10.1103/PhysRevB.86.064405
Publication status	Published - 3 Aug 2012

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Baker, M. L., Waldmann, O., Piligkos, S., Bircher, R., Cador, O., Carretta, S., Collison, D., Fernandez-Alonso, F., McInnes, E. J. L., Mutka, H., Podlesnyak, A., Tuna, F., Ochsenbein, S., Sessoli, R., Sieber, A., Timco, G. A., Weihe, H., Güdel, H. U., & Winpenny, R. E. P. (2012). Inelastic neutron scattering studies on the odd-membered antiferromagnetic wheel Cr₈Ni. Physical Review B Condensed Matter, 86(6), Article 064405. https://doi.org/10.1103/PhysRevB.86.064405

Baker, ML, Waldmann, O, Piligkos, S, Bircher, R, Cador, O, Carretta, S, Collison, D, Fernandez-Alonso, F, McInnes, EJL, Mutka, H, Podlesnyak, A, Tuna, F, Ochsenbein, S, Sessoli, R, Sieber, A, Timco, GA, Weihe, H, Güdel, HU & Winpenny, REP 2012, 'Inelastic neutron scattering studies on the odd-membered antiferromagnetic wheel Cr₈Ni', Physical Review B Condensed Matter, vol. 86, no. 6, 064405. https://doi.org/10.1103/PhysRevB.86.064405

@article{4ac9afd2d9884e8dac264b88dbc852e0,

title = "Inelastic neutron scattering studies on the odd-membered antiferromagnetic wheel Cr8Ni",

abstract = "[ (iC 3H 7)2NH 2][Cr 8NiF 9(O 2CCMe)18], or Cr 8Ni, is a prominent example of an odd-membered antiferromagnetic {"}wheel.{"} A detailed characterization of the magnetic properties of Cr 8Ni has been conducted. Inelastic neutron scattering (INS) is used to investigate the energy and momentum transfer dependence of the low-lying spin excitations, including excited states inaccessible by other experimental techniques. The richness of the INS data, in conjunction with microscopic spin Hamiltonian simulations, enables an accurate characterization of the magnetic properties of Cr 8Ni. Nearest-neighbor exchange constants of J CrCr = 1.31 meV and J CrNi = 3.22 meV are determined, and clear evidence of axial single-ion anisotropy is found. The parameters determined by INS are shown to fit magnetic susceptibility. The spectroscopic identification of several successive S=1 excited total spin states and lowest spin band excitations show that the rotational band picture, valid for bipartite AFM wheels, breaks down for this odd-numbered wheel. The exchange constants determined here differ from previous efforts based on bulk measurements, and possible reasons are discussed. The large J CrNi/J CrCr ratio in Cr 8Ni puts this wheel into a regime with strong quantum fluctuations in which the ground state can be described with a valence bond solid state picture.",

author = "Baker, {Michael L.} and Oliver Waldmann and Stergios Piligkos and Roland Bircher and Olivier Cador and Stefano Carretta and David Collison and Felix Fernandez-Alonso and McInnes, {Eric J.L.} and Hannu Mutka and Andrew Podlesnyak and Floriana Tuna and Stefan Ochsenbein and Roberta Sessoli and Andreas Sieber and Timco, {Grigore A.} and H{\o}gni Weihe and G{\"u}del, {Hans U.} and Winpenny, {Richard E.P.}",

year = "2012",

month = aug,

day = "3",

doi = "10.1103/PhysRevB.86.064405",

language = "English",

volume = "86",

journal = "Physical Review B Condensed Matter",

issn = "0163-1829",

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TY - JOUR

T1 - Inelastic neutron scattering studies on the odd-membered antiferromagnetic wheel Cr8Ni

AU - Baker, Michael L.

AU - Waldmann, Oliver

AU - Piligkos, Stergios

AU - Bircher, Roland

AU - Cador, Olivier

AU - Carretta, Stefano

AU - Collison, David

AU - Fernandez-Alonso, Felix

AU - McInnes, Eric J.L.

AU - Mutka, Hannu

AU - Podlesnyak, Andrew

AU - Tuna, Floriana

AU - Ochsenbein, Stefan

AU - Sessoli, Roberta

AU - Sieber, Andreas

AU - Timco, Grigore A.

AU - Weihe, Høgni

AU - Güdel, Hans U.

AU - Winpenny, Richard E.P.

PY - 2012/8/3

Y1 - 2012/8/3

N2 - [ (iC 3H 7)2NH 2][Cr 8NiF 9(O 2CCMe)18], or Cr 8Ni, is a prominent example of an odd-membered antiferromagnetic "wheel." A detailed characterization of the magnetic properties of Cr 8Ni has been conducted. Inelastic neutron scattering (INS) is used to investigate the energy and momentum transfer dependence of the low-lying spin excitations, including excited states inaccessible by other experimental techniques. The richness of the INS data, in conjunction with microscopic spin Hamiltonian simulations, enables an accurate characterization of the magnetic properties of Cr 8Ni. Nearest-neighbor exchange constants of J CrCr = 1.31 meV and J CrNi = 3.22 meV are determined, and clear evidence of axial single-ion anisotropy is found. The parameters determined by INS are shown to fit magnetic susceptibility. The spectroscopic identification of several successive S=1 excited total spin states and lowest spin band excitations show that the rotational band picture, valid for bipartite AFM wheels, breaks down for this odd-numbered wheel. The exchange constants determined here differ from previous efforts based on bulk measurements, and possible reasons are discussed. The large J CrNi/J CrCr ratio in Cr 8Ni puts this wheel into a regime with strong quantum fluctuations in which the ground state can be described with a valence bond solid state picture.

AB - [ (iC 3H 7)2NH 2][Cr 8NiF 9(O 2CCMe)18], or Cr 8Ni, is a prominent example of an odd-membered antiferromagnetic "wheel." A detailed characterization of the magnetic properties of Cr 8Ni has been conducted. Inelastic neutron scattering (INS) is used to investigate the energy and momentum transfer dependence of the low-lying spin excitations, including excited states inaccessible by other experimental techniques. The richness of the INS data, in conjunction with microscopic spin Hamiltonian simulations, enables an accurate characterization of the magnetic properties of Cr 8Ni. Nearest-neighbor exchange constants of J CrCr = 1.31 meV and J CrNi = 3.22 meV are determined, and clear evidence of axial single-ion anisotropy is found. The parameters determined by INS are shown to fit magnetic susceptibility. The spectroscopic identification of several successive S=1 excited total spin states and lowest spin band excitations show that the rotational band picture, valid for bipartite AFM wheels, breaks down for this odd-numbered wheel. The exchange constants determined here differ from previous efforts based on bulk measurements, and possible reasons are discussed. The large J CrNi/J CrCr ratio in Cr 8Ni puts this wheel into a regime with strong quantum fluctuations in which the ground state can be described with a valence bond solid state picture.

U2 - 10.1103/PhysRevB.86.064405

DO - 10.1103/PhysRevB.86.064405

M3 - Journal article

SN - 0163-1829

VL - 86

JO - Physical Review B Condensed Matter

JF - Physical Review B Condensed Matter

IS - 6

M1 - 064405

ER -

Inelastic neutron scattering studies on the odd-membered antiferromagnetic wheel Cr8Ni

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Inelastic neutron scattering studies on the odd-membered antiferromagnetic wheel Cr₈Ni