Large stoichiometric and nonstoichiometric single crystals of the gadolinium monopnictides GdX (X = P, As, Sb, Bi) have been grown for the first time by the mineralization method. Magnetic and transport properties of stoichiometric and nonstoichiometric samples are found to be very different. The weak ferromagnetism and the negative magnetoresistivity observed in nonstoichiometric samples of GdP and GdAs at low temperatures and low magnetic fields can be considered as clear evidence of the formation of trapped magnetic polaron states in gadolinium monopnictide systems.
- A. magnetically ordered materials
- D. electronic transport
- D. exchange and superexchange
- D. recombination and trapping