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Register a new userAnisotropy of the molecular magnet V$_{15}$ spin Hamiltonian detected by high-field electron spin resonance
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The molecular compound K$_6$[V$^{IV}_{15}$As$^{III}_6$O$_{42}$(H$_2$O)] $cdot$ 8H$_2$O, in short V$_{15}$, has shown important quantum effects such as coherent spin oscillations. The details of the spin quantum dynamics depend on the exact form of the spin Hamiltonian. In this study, we present a precise analysis of the intramolecular interactions in V$_{15}$. To that purpose, we performed high-field electron spin resonance measurements at 120 GHz and extracted the resonance fields as a function of crystal orientation and temperature. The data are compared against simulations using exact diagonalization to obtain the parameters of the molecular spin Hamiltonian.
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We present muon spin lattice relaxation measurements in the V15 spin 1/2 molecular nano-magnet. We find that the relaxation rate in low magnetic fields (<5 kG) is temperature independent below ~10 K, implying that the molecular spin is dynamically fluctuating down to 12 mK. These measurements show that the fluctuation time increases as the temperature is decreased and saturates at a value of ~6 nsec at low temperatures. The fluctuations are attributed to V15 molecular spin dynamics perpendicular to the applied magnetic field direction, induced by coupling between the molecular spin and nuclear spin bath in the system.
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