Esr of heavily neutron-transmutation-doped germanium

Integrated electron spin resonance is used to monitor the magnetic properties of the electron spin in a sample of NTD Ge,using temperatures down to 40 mK and uniaxial stresses up to 0.36 GPa. The sample density is just below the critical density at ambient stress for the metal-non-metal transition The electron spin susceptibility under stress shows no temperature variation; a small broadening as T is lowered is matched by a similar decrease of intensity. Further,< 110 > uniaxial stress enhances the intensity of the esr line. The contrast with Si:P is discussed. A large 'stress-tuning' effect is inferred.