相关论文: Observation of a Distribution of Internal Transver…
The spin relaxation in the molecular magnet \Mn12 is investigated by a novel type of high-frequency magnetic spectroscopy. By reversing the external magnetic field the intensities of the $|\pm 10>\to |\pm 9>$ transitions within the ground…
The symmetry of magnetic quantum tunneling (MQT) in the single molecule magnet Mn12-acetate has been determined by sensitive low-temperature magnetic measurements in the pure quantum tunneling regime and high frequency EPR spectroscopy in…
We have studied the crossover between thermally assisted and pure quantum tunneling in single crystals of high spin (S=10) uniaxial single molecule magnet Mn12-acetate using micro-Hall effect magnetometry. Magnetic hysteresis experiments…
The variation with microwave frequency and temperature of previously reported anomalous peaks in the EPR spectra of Mn12-acetate, under large transverse fields, reveals that the molecular easy magnetization axes are tilted with respect to…
Comprehensive theory of quantum spin relaxation in Mn-12 acetate crystals is developed, that takes into account imperfections of the crystal structure and is based upon the generalization of the Landau-Zener effect for incoherent tunneling…
A Landau-Zener multi-crossing method has been used to investigate the tunnel splittings in high quality Mn$_{12}$-acetate single crystals in the pure quantum relaxation regime and for fields applied parallel to the magnetic easy axis. With…
In this work, we study the spin dynamics of Mn12-acetate molecules in the regime of thermally assisted tunneling. In particular, we describe the system in the presence of a strong transverse magnetic field. Similar to recent experiments,…
Below 360 mK, Fe magnetic molecular clusters are in the pure quantum relaxation regime and we show that the predicted square-root time relaxation is obeyed, allowing us to develop a new method for watching the evolution of the distribution…
We review our studies of the effect of transverse fields on the susceptibility and magnetization of single crystals of the prototype single molecule magnet (SMM), Mn$_{12}$-acetate, and of a new high-symmetry variant,…
The symmetry of magnetic quantum tunneling has been studied in the prototype single molecule magnet Mn$_{12}$-acetate using a micro-Hall effect magnetometer and superconducting high field vector magnet system. An average crystal fourfold…
A Mn4 single-molecule magnet (SMM), with a well isolated spin ground state of S = 9/2, is used as a model system to study Landau-Zener (LZ) tunneling in the presence of weak intermolecular dipolar and exchange interactions. The anisotropy…
The crossover between thermally assisted and pure quantum tunneling has been studied in single crystals of high spin (S=10) uniaxial molecular magnet Mn12 using micro-Hall-effect magnetometry. Magnetic hysteresis and relaxation experiments…
The nuclear spin-mediated quantum relaxation of ensembles of tunneling magnetic molecules causes a 'hole' to appear in the distribution of internal fields in the system. The form of this hole, and its time evolution, are studied using Monte…
We use neutron diffraction to probe the magnetization components of a crystal of Mn12 single-molecule magnets. Each of these molecules behaves, at low temperatures, as a nanomagnet with spin S = 10 and strong anisotropy along the…
The magnetic properties of a monolayer of Mn12 single molecule magnets grafted onto a Si substrate have been investigated using depth-controlled $\beta$-detected nuclear magnetic resonance. A low energy beam of spin polarized radioactive…
Current theories still fail to give a satisfactory explanation of the observed quantum phenomena in the relaxation of the magnetisation of the molecular cluster Mn12 acetate. In the very low temperature regime, Prokof'ev and Stamp recently…
We report measurements and theoretical analysis of resonant spin tunneling in randomly oriented nanospheres of a molecular magnet. Amorphous nanospheres of Mn$_{12}$ acetate have been fabricated and characterized by chemical, infrared, TEM,…
Inelastic tunneling through magnetically anisotropic molecules is studied theoretically in the presence of a strong magnetic field. Since the molecular orientation is not well controlled in tunneling experiments, we consider arbitrary…
Magnetic relaxation in molecular magnets under a sweeping field is studied by taking into account local stray fields. It is found that the randomness of local stray field leads to a distribution of the relaxation rate which subsequently…
The behavior of molecular nanomagnets in periodic magnetic field transverse to the easy axis direction is investigated. It is shown that at sufficiently strong field the tunneling time can be considerably reduced.