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Electrical conductors can be chiral, i.e., can exist in two forms where one is the other's mirror image. Thus far, no effect of chirality on magnetotransport has been observed. We argue that the electrical resistance of any chiral conductor should depend linearly both on the external magnetic field and the current through the conductor and on its handedness. We suggest two mechanisms to carry this effect and show experimentally on model systems that both are effective.

The magnetic state of a ferromagnet can affect the electrical transport properties of the material; for example, the relative orientation of the magnetic moments in magnetic multilayers underlies the phenomenon of giant magnetoresistance. The inverse effect--in which a large electrical current density can perturb the magnetic state of a multilayer--has been predicted and observed experimentally with point contacts and lithographically patterned samples. Some of these observations were taken as indirect evidence for current-induced excitation of spin waves, or 'magnons'. Here we probe directly the high-frequency behaviour and partial phase coherence of such current-induced excitations, by externally irradiating a point contact with microwaves. We determine the magnon spectrum and investigate how the magnon frequency and amplitude vary with the exciting current. Our observations support the feasibility of a spin-wave maser' or 'SWASER' (spin-wave amplification by stimulated emission of radiation).

In the electrical Hall effect, a magnetic field, applied perpendicular to an electrical current, induces through the Lorentz force a voltage perpendicular to the field and the current. It is generally assumed that an analogous effect cannot exist in the phonon thermal conductivity, as there is no charge transport associated with phonon propagation. In this Letter, we argue that such a magnetotransverse thermal effect should exist and experimentally demonstrate this "phonon Hall effect" in Tb3Ga5O12.

Introduction 175 4.2. Magnetization of small superconducting particles 2. Phenomenological description of small particles 178 4.3. Microscopic theory of small superconductors 2.1. Interaction with electromagnetic radiation 178 4.4. Fluctuations in small superconducting particles 2.2. Mie's theory 178 5. Preparation of small particles 2.3. The dielectric constant of a small metallic particle 184 5.1. Metal colloids 2.4. The effective dielectric constant of the embedding 5.2. Granular metal films medium 189 5.3. Particles prepared by the gas-evaporation technique 3. Quantum size effects in small metallic particles 192 5.4. Particles prepared by nucleation and growth in a 3.1. Microscopic description of electrons in small particles 192 matrix 273 3.2. Kubo's small particle 197 5.5. Impregnated porous materials 275 3.3. Level statistics 201 Appendix I. Thermodynamic calculations for Kubo's small 3.4. Spectroscopy of the small particle level structure 213 particle 3.5. Experiments 217 Appendix II. Thermodynamic calculations for the particle 4. Superconductivity in small particles 232 with equal level spacing 4.1. Characteristic lengths of superconductors 232 References

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