Angular dependence of the magnetic susceptibility in the itinerant metamagnetSr3Ru2O7

We report the results of a study of the differential magnetic susceptibility of ${\mathrm{Sr}}_3{\mathrm{Ru}}_2{\mathrm{O}}_7$ as a function of temperature and magnetic fields applied at a series of angles to the $\mathrm{ab}$ plane. By analyzing the real and imaginary parts of the susceptibility, we conclude that the field angle acts as a continuous tuning parameter for the critical end point to a line of first-order metamagnetic phase transitions. The end point sits at $\approx 1.25\mathrm{K}$ for fields applied in the $\mathrm{ab}$ plane, and is depressed to below 50 mK when the field is aligned within $10°$ of the c axis.