Solid State Systems for Electron Electric Dipole Moment and other Fundamental Measurements

In 1968, F.L. Shapiro published the suggestion that one could search for an electron EDM by applying a strong electric field to a substance that has an unpaired electron spin; at low temperature, the EDM interaction would lead to a net sample magnetization that can be detected with a SQUID magnetometer. One experimental EDM search based on this technique was published, and for a number of reasons including high sample conductivity, high operating temperature, and limited SQUID technology, the result was not particularly sensitive compared to other experiments in the late 1970's. Advances in SQUID and conventional magnetometery had led us to reconsider this type of experiment, which can be extended to searches and tests other than EDMs (e.g., test of Lorentz invariance). In addition, the complementary measurement of an EDM-induced sample electric polarization due to application of a magnetic field to a paramagnetic sample might be effective using modern ultrasensitive charge measurement techniques. A possible paramagnetic material is Gd-substituted YIG which has very low conductivity and a net enhancement (atomic enhancement times crystal screening) of order unity. Use of a reasonable volume (100's of cc) sample of this material at 50 mK and 10 kV/cm might yield an electron EDM sensitivity of $10^{-33}$ e cm or better, a factor of $10^6$ improvement over current experimental limits.Comment: 6 pages. Prepared for ITAMP workshop on fundamental physics that was to be held Sept 20-22 2001 in Cambride, MA, but was canceled due to terrorist attack on U.S New version incorporates a number of small changes, most notably the scaling of the sensitivity of the Faraday magnetometer with linewidth is now treated in a saner fashion. The possibility of operating at an even lower temperarture, say 10 microkelvin, is also discusse

Frequency Dependence of Magnetoelectric Interactions in Layered Structures of Ferromagnetic Alloys and Piezoelectric Oxides

Magnetoelectric (ME) interactions in layered structures of magnetostrictive and piezoelectric phases are mediated by mechanical deformation. Here we discuss the frequency dependence of ME coupling in bilayers and trilayers of Permendur, a ferromagnetic alloy, and lead zirconate titanate. Data on ME voltage coefficient versus frequency profiles reveal a giant ME coupling at electromechanical resonance. The maximum voltage coefficient of 90 V/cm Oe is three orders of magnitude higher than low-frequency values. The ME interactions for transverse fields is an order of magnitude stronger than for longitudinal fields. These results are in agreement with theory. The resonance ME effect, therefore, is a novel tool for enhancing the magnetic-to-electric field conversion efficiency in the composites.Comment: accepted for publication as rapid communication in Applied Physics

Microscopic mechanisms of spin-dependent electric polarization in 3d oxides

We present a short critical overview of different microscopic models for nonrelativistic and relativistic magnetoelectric coupling including the so-called "spin current scenario", ab-initio calculations, and several recent microscopic approaches to a spin-dependent electric polarization in 3d oxides.Comment: 8 pages, 3 figure

ECHELLE PROVISOIRE DE TEMPERATURE DE 1976 ENTRE 0,5 K ET 30 K

Il est devenu de plus en plus évident que les échelles à pression de vapeur de l'hélium utilisées couramment /1,2/ et l'extrémité inférieure de l'Echelle Internationale Pratique de Température de 1968 (EIPT-68) /3/ s'écartent nettement de la température thermodynamique et, de plus, qu'elles ne sont pas cohérentes entre elles. Le Comité Consultatif de Thermométrie (CCT) a pris connaissance et discuté de ces problèmes posés par les échelles internationales pratiques de température actuellement utilisées. En 1976, le CCT a donc proposé au Comité International des Poids et mesures (CIPM)que soit recommandée pour être utilisée sur le plan international, une nouvelle échelle provisoire pratique de température entre 0,5 K et 30 K jusqu'à ce que l'on puisse adopter une nouvelle Echelle Internationale Pratique de Température /4/. Le CIPM a autorisé le CCT à publier l' "Echelle Provisoire de Température de 1976 entre 0,5 K et 30 K" (EPT-76) lorsqu'elle serait sous sa forme définitive /5,6/. Cette échelle est décrite ci-après