Role Of Magnetic Interactions Research Articles

ARM, TRM and magnetic interactions: Concentration dependence

ARM (anhysteretic remanence)/SIRM (saturation isothermal remanence) and TRM (thermoremanence)/SIRM were measured as a function of the concentration (volume fraction) of single-domain magnetite ( 3 × 10 −6 ≲ C ≲ 2 × 10 −2 ), ARM/SIRM increases with decreasing concentration, showing that there is magnetic interaction between fine particles. The role of magnetic interaction in TRM acquisition is also important at higher concentrations of magnetite ( C ≳ 0.1%), where the value of TRM/SIRM increases with decreasing concentration. It is only for concentrations of C ≲ 0.1% that the value of TRM/SIRM is fairly constant and interactions among magnetite grains seem to be ignored. The ratio TRM/ARM decreases from seven to almost unity as the concentration of magnetite decreases.