Myriam Paula Sarachik

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For about twenty years, it has been the prevailing view that there can be no metallic state or metal-insulator transition in two dimensions in zero magnetic field. In the last several years, however, unusual behavior suggestive of such a transition has been reported in a variety of dilute two-dimensional electron and hole systems. The physics behind these(More)
Local time-resolved measurements of fast reversal of the magnetization of single crystals of Mn12-acetate indicate that the magnetization avalanche spreads as a narrow interface that propagates through the crystal at a constant velocity that is roughly 2 orders of magnitude smaller than the speed of sound. We argue that this phenomenon is closely analogous(More)
In magnetic fields applied parallel to the anisotropy axis, the relaxation of the magnetization of Mn(12)-acetate measured for different sweep rates collapses onto a single scaled curve. The form of the scaling implies that the dominant symmetry-breaking process responsible for tunneling is a locally varying second-order transverse anisotropy, forbidden by(More)
For the past two decades, all two-dimensional systems of electrons were believed to be insulating in the limit of zero temperature. Recent experiments provide evidence for an unexpected transition to a conducting phase at very low electron densities. The nature of this phase is not understood and is currently the focus of intense theoretical and(More)
With decreasing density n(s) the thermopower S of a low-disorder two-dimensional electron system in silicon is found to exhibit a sharp increase by more than an order of magnitude tending to a divergence at a finite disorder-independent density n(t) consistent with the critical form (-T/S) is proportional to (n(s)-n(t))(x) with x=1.0±0.1 (T is the(More)
For a broad range of electron densities n and temperatures T, the in-plane magnetoconductivity of the two-dimensional system of electrons in silicon MOSFETs can be scaled onto a universal curve with a single parameter H(sigma)(n,T), where H(sigma) obeys the empirical relation H(sigma) = A(n) [Delta(n)(2)+T2](1/2). The characteristic energy k(B)Delta(More)
The low-temperature dc conductivities of barely metallic samples of ptype Si:B are compared for a series of samples with different dopant concentrations, n, in the absence of stress (cubic symmetry), and for a single sample driven from the metallic into the insulating phase by uniaxial compression, S. For all values of temperature and stress, the(More)
Bo Wen,1 P. Subedi,2 Lin Bo,1 Y. Yeshurun,1,2,3 M. P. Sarachik,1 A. D. Kent,2 A. J. Millis,4 C. Lampropoulos,5 and G. Christou5 1Department of Physics, City College of New York, CUNY, New York, New York 10031, USA 2Department of Physics, New York University, New York, New York 10003, USA 3Department of Physics, Institute of Nanotechnology, Bar-Ilan(More)
We report the first observation of steps in the hysteresis loop of a high-spin molecular magnet. We propose that the steps, which occur every 0.46 T, are due to thermally assisted resonant tunneling between different quantum spin states. Magnetic relaxation increases dramatically when the field is in the neighborhood of a step. A simple model accounts for(More)
The zero-temperature magnetoconductivity of just-metallic Si:P scales with magnetic field H and dopant concentration n lying on a single universal curve: s(n ,H)/s(n ,0)5G@HDn# with a magnetic-field crossover exponent d'2. We note that Si:P, Si:B, and Si:As all have unusually large crossover exponents near 2, and suggest that this anomalously weak response(More)