Magnetic properties of wurtzite (Ga,Mn)As

摘要: Abstract Here we report on detailed studies of the magnetic properties wurtzite (Ga,Mn)As cylindrical shells. Ga0.94Mn0.06As shells have been grown by molecular beam epitaxy at low temperature as a part multishell cylinders overgrown (Ga,In)As nanowires cores, synthesized GaAs (111)B substrates. Our clearly indicate presence ferromagnetic coupling, which despite reasonably high Mn contents 6% is limited only to below 30 K. A set dedicated measurements shows that structural quality material order has granular form, gives rise dynamical slow-down characteristic blocked superparamagnets. The lack long range assigned very hole density, caused primarily numerous compensation donors, arsenic antisites, formed in due specific geometry growth nanowire template. associated electrostatic disorder patchwork spontaneously magnetized (macrospin) and nonmagnetic (paramagnetic) volumes material. Using field results it evaluated total volume taken macrospins constitute about 2/3 whereas remaining 1/3 paramagnetic ions reside. By establishing number uncoupled two contributions were separated. Arrott plot method applied superparamagnetic yielded first experimental assessment magnitude spin–spin coupling within (Ga,Mn)As, T C = 28 K. In broader view our an important contribution still ongoing dispute true dominant form(s) magnetism this model dilute semiconductor.