Susceptibility of two-, three-, and four-dimensional spin glasses in a magnetic field

Through Monte Carlo simulations we have studied the spin-glass susceptibility of two-, three-, and four-dimensional spin glasses in a magnetic field. We find that in four dimensions curves of constant susceptibility curve upward as the temperature is lowered, in a manner indicative of the presence of a de Almeida--Thouless (AT) line of phase transitions. In three dimensions the curves of constant susceptibility also appear to curve up, although not as sharply. In contrast, in two dimensions we do not see indications of an AT line.