Low temperature magnetic properties and spin dynamics in single crystals of Cr8Zn antiferromagnetic molecular rings

Abstract

Articles you may be interested inHigh temperature spin dynamics in linear magnetic chains, molecular rings, and segments by nuclear magnetic resonance J. Appl. Phys. 117, 17B308 (2015) A detailed experimental investigation of the effects giving rise to the magnetic energy level structure in the vicinity of the level crossing (LC) at low temperature is reported for the open antiferromagnetic molecular ring Cr 8 Zn. The study is conducted by means of thermodynamic techniques (torque magnetometry, magnetization and specific heat measurements) and microscopic techniques (nuclear magnetic resonance line width, nuclear spin lattice, and spin-spin relaxation measurements). The experimental results are shown to be in excellent agreement with theoretical calculations based on a minimal spin model Hamiltonian, which includes a Dzyaloshinskii-Moriya interaction. The first ground state level crossing at µ 0 H c1 = 2.15 T is found to be an almost true LC while the second LC at µ 0 H c2 = 6.95 T has an anti-crossing gap of ∆ 12 = 0.19 K. In addition, both NMR and specific heat measurements show the presence of a level anti-crossing between excited states at µ 0 H = 4.5 T as predicted by the theory. In all cases, the fit of the experimental data is improved by introducing a distribution of the isotropic exchange couplings (J), i.e., using a J strain model. The peaks at the first and second LCs in the nuclear spin-lattice relaxation rate are dominated by inelastic scattering and a value of Γ ∼ 10 10 rad/s is inferred for the life time broadening of the excited state of the open ring, due to spin phonon interaction. A loss of NMR signal (wipe-out effect) is observed for the first time at LC and is explained by the enhancement of the spin-spin relaxation rate due to the inelastic scattering. C 2015 AIP Publishing LLC. [http://dx

Half‐Integer Spin Triangles: Old Dogs, New Tricks

“…[159,160] However, J-strainsa re more difficult to assess and much less documented. [161][162][163] This difficulty finds its exception in the case of spin triangles. The extreme sensitivity of the spin density distributions on the J/J' ratio, and the similarly extreme sen- sitivity of the g ?…”

“…However, J ‐strains are more difficult to assess and much less documented [161–163] . This difficulty finds its exception in the case of spin triangles.…”

A heterometallic [LnLn′Ln] lanthanide complex as a qubit with embedded quantum error correction

“…[7][8][9][10] Each molecule can host several distinguishable qubits, with chemically tailored magnetic interactions, [11][12][13][14][15][16] and can show remarkably long coherence times. [17][18][19][20][21][22][23][24][25][26][27] In addition, they can be characterized and manipulated by radiofrequency 26,28,29 and electron paramagnetic resonance (EPR) pulses addressing different transitions, 30 as already probed even on individual atoms on surfaces. 31 Here, we propose to exploit these peculiarities in order to embed a protected logical unit into the three weakly coupled effective spins 1/2 located within the same molecule.…”

Relaxation dynamics in the frustratedCr9antiferromagnetic ring probed by NMR

“…The graph shows that with our calculations it is possible to reproduce the wipeout effect, confirming the reliability of our model. The bottom panel of Fig.3 shows that we predict a level crossing between the first and the second excited levels of Cr 9 at about 5.4 T. At the level crossings there is a strong increase of both 1/T 1 and 1/T 2 due to inelastic contributions to the relaxation dynamics, thus we expect a strong wipeout effect 40 . We have therefore measured M H xy (0)T as a function of the applied magnetic field at T = 8 K, in order to populate the lowest excited levels involved in the crossing.…”