Specific heat of a three-dimensional metal near a zero-temperature magnetic phase transition with dynamic exponentz=2, 3, or 4

We derive expressions for the universal contribution to the specific heat of a three-dimensional metal near a zero-temperature phase transition with dynamic exponent $z=2,3$, or 4. The results allow a quantitative comparison of theory to data. We illustrate the application of our results by analyzing data for Ce$_{1-x}$Lu$_x$Cu$_2$Si$_2$, which has been claimed to be near a quantum critical point.Comment: 23 pages, revtex. For figures, send mail to millis@physics.att.co