Heat Capacity Reveals the Physics of a Frustrated Spin Tube

Ivanov, N. B.; Schnack, Jürgen; Schnalle, Roman; Richter, Johannes; Kögerler, Paul; Newton, Graham N.; Cronin, Leroy; Oshima, Yoshiteru; Nojiri, Hiroyuki

doi:10.1103/physrevlett.105.037206

Cited by 51 publications

(32 citation statements)

References 29 publications

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“…At this point a further link between molecular nanomagnets and quantum spin systems emerges, as not only small clusters may be incorporated into the network but also large clusters or molecular nanomagnets, which should be expected to result in an interesting interplay between the complex quantum states realized within a cluster and the complex phases generated in extended lattices. Indeed, the synthesis of extended exchange-coupled networks of, e.g., Cu 3 molecular units or single-molecule magnets have already been reported (Ivanov et al, 2010;Miyasaka et al, 2006;Morimoto et al, 2009). All in all, the competition between the quantum states in a magnetic cluster and the cooperativity introduced through an extended network of inter -cluster interactions should continue to be an attractive playground for research.…”

Section: Discussionmentioning

confidence: 99%

Magnetic Cluster Excitations

Fürrer

2010

Int. J. Mod. Phys. B

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Magnetic clusters, i.e., assemblies of a finite number (between two or three and several hundred) of interacting spin centers which are magnetically decoupled from their environment, can be found in many materials ranging from inorganic compounds, magnetic molecules, artificial metal structures formed on surfaces to metalloproteins. The magnetic excitation spectra in them are determined by the nature of the spin centers, the nature of the magnetic interactions, and the particular arrangement of the mutual interaction paths between the spin centers. Small clusters of up to four magnetic ions are ideal model systems to examine the fundamental magnetic interactions which are usually dominated by Heisenberg exchange, but often complemented by anisotropic and/or higher-order interactions. In large magnetic clusters which may potentially deal with a dozen or more spin centers, the possibility of novel many-body quantum states and quantum phenomena are in focus. In this review the necessary theoretical concepts and experimental techniques to study the magnetic cluster excitations and the resulting characteristic magnetic properties are introduced, followed by examples of small clusters demonstrating the enormous amount of detailed physical information which can be retrieved. The current understanding of the excitations and their physical interpretation in the molecular nanomagnets which represent large magnetic clusters is then presented, with an own section devoted to the subclass of the singlemolecule magnets which are distinguished by displaying quantum tunneling of the magnetization. Finally, some quantum many-body states are summarized which evolve in magnetic insulators characterized by built-in or field-induced magnetic clusters. The review concludes addressing future perspectives in the field of magnetic cluster excitations.

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Section: Discussionmentioning

confidence: 99%

Magnetic Cluster Excitations

Fürrer

2010

Int. J. Mod. Phys. B

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“…The Lieb-Schultz-Mattis theorem [24] would suggest that the spin gap must be accompanied with at least doublydegenerate ground state with a spontaneous breaking of the translational symmetry since the unit cell consists of three spins. From the experimental point of view, 1D coordination polymers [(CuCl 2 tachH) 3 Cl]Cl 2 (tach=1,3,5-triaminocyclohexane) [25][26][27] and Cu 2 Cl 4 · D 8 C 4 SO 2 [28] provide unique experimental realizations of a spin-1/2 Heisenberg three-leg and four-leg tube, respectively.…”

Section: Introductionmentioning

confidence: 99%

Spin frustration of a spin-1/2 Ising–Heisenberg three-leg tube as an indispensable ground for thermal entanglement

Strečka

Alécio

Lyra

et al. 2016

Journal of Magnetism and Magnetic Materials

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The spin-1/2 Ising-Heisenberg three-leg tube composed of the Heisenberg spin triangles mutually coupled through the Ising inter-triangle interaction is exactly solved in a zero magnetic field. By making use of the local conservation for the total spin on each Heisenberg spin triangle the model can be rigorously mapped onto a classical composite spin-chain model, which is subsequently exactly treated through the transfer-matrix method. The ground-state phase diagram, correlation functions, concurrence, Bell function, entropy and specific heat are examined in detail. It is shown that the spin frustration represents an indispensable ground for a thermal entanglement, which is quantified with the help of concurrence. The specific heat displays diverse temperature dependences, which may include a sharp low-temperature peak mimicking a temperature-driven first-order phase transition. It is convincingly evidenced that this anomalous peak originates from massive thermal excitations from the doubly degenerate ground state towards an excited state with a high macroscopic degeneracy due to chiral degrees of freedom of the Heisenberg spin triangles.

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“…Recently the specific heat of the system has been measured down to 0.1 K, 52 confirming no three dimensional magnetic ordering under zero magnetic field down to 0.1 K. The temperature dependence of specific heat shows a broad peak around 2 K and rapid decrease below the peak with decreasing temperature. Below 0.5 K, the specific heat is almost proportional to T , which indicates a gapless ground state of the system.…”

Section: B Spin Dynamics In the Spin Tubementioning

confidence: 93%

Review of NMR studies of nanoscale molecular magnets composed of geometrically frustrated antiferromagnetic triangles

Furukawa

2016

IJNT

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We present a comprehensive review of nuclear magnetic resonance (NMR) studies performed on three nanoscale molecular magnets with different configurations of geometrically frustrated antiferromagnetic (AFM) triangles, new spin frustration systems with different novel structures: (1) the isolated single AFM triangle K6[V15As6O42(H2O)]·8H2O (in short V15), (2) the spin ball [Mo72Fe30O252(Mo2O7(H2O))2 (Mo2O8H2(H2O))(CH3COO)12(H2O)91]·150H2O (in short Fe30 spin ball), and (3) the twisted triangular spin tube [(CuCl2tachH)3Cl]Cl2 (in short Cu3 spin tube). In the V15 nanomagnet, from 51 V NMR spectra observed at only below ∼ 0.1 K, we directly determined the local spin configuration in both the nonfrustrated total spin ST = 3/2 state at higher magnetic fields (H ≥ 2.7 T) and the two nearly degenerate ST = 1/2 ground states at lower magnetic fields (H ≤ 2.7 T). The dynamical magnetic properties of V15 were investigated by proton spin-lattice relaxation rate (1/T1) measurements. In the ST = 3/2 state, 1/T1 shows thermally activated behavior as a function of temperature. On the other hand, a temperature independent behavior of 1/T1 at very low temperatures is observed in the frustrated ST = 1/2 ground state below 2.7 Tesla. Possible origins for the peculiar behavior of 1/T1 will be discussed in terms of magnetic fluctuations due to spin frustrations. In Fe30 spin ball, static and dynamical properties of Fe 3+ (s = 5/2) have been investigated by proton NMR spectra and 1/T1 measurements. From the temperature dependence of 1/T1, the fluctuation frequency of the Fe 3+ spins is found to decrease with decreasing temperature, indicating spin freezing at low temperatures. The spin freezing is also evidenced by the observation of a sudden broadening of 1 H NMR spectra below 0.6 K. Finally 1 H NMR data in the Cu spin tube will be described. An observation of magnetic broadening of 1 H NMR spectra at low temperatures below 1 K directly revealed a gapless ground state of the system. The 1/T1 measurements revealed an usual slow spin dynamics in the quasi one dimensional Cu3 spin tube.

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Heat Capacity Reveals the Physics of a Frustrated Spin Tube

Cited by 51 publications

References 29 publications

Magnetic Cluster Excitations

Magnetic Cluster Excitations

Spin frustration of a spin-1/2 Ising–Heisenberg three-leg tube as an indispensable ground for thermal entanglement

Review of NMR studies of nanoscale molecular magnets composed of geometrically frustrated antiferromagnetic triangles

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