Piezomagnetic behaviour in α-Fe2O3 nanofilms grown within nanochannels of Na-4 mica

• Published in: Journal of magnetism and magnetic materials 2016-03, Vol.402, p.64-68
• Main Authors: Maiti, Ramaprasad, Chatterjee, Soumi, Saha, Shyamal Kumar, Mitra, Manoj kumar, Chakravorty, Dipankar
• Format: Article
• Language: English
• Subjects: Compressive stress; Na-4 mica-αFe2O3 composite; Piezomagnetic; Thermal expansion coefficient
• ISSN: 0304-8853
• DOI: 10.1016/j.jmmm.2015.11.049

α-Fe2O3 nanofilms were grown within the 0.6nm width nanochannels of sodium fluorophlogopite mica (Na-4 mica) structure. Due to a large difference in the values of thermal expansion coefficients of Na-4 mica and α-Fe2O3 a huge compressive stress was generated on the latter as the composite was cooled from 1023K to 300K. Magnetization measurements on the composite as a function of temperature showed the presence of piezomagnetic effect in α-Fe2O3. The values of piezomagnetic coefficient were estimated to be in the range 2.3×10−6 to 3.4×10−4emu/gkg/cm2. This is of the same order as that reported earlier by work carried out on single crystals of macrodimensions. Magnetization measurements of α-Fe2O3 particles of diameter ~130nm on the other hand, showed the usual behaviour viz., a magnetic phase transition from antiferromagnetic to ferromagnetic state at 237K. •Growth of α-Fe2O3 within nanochannels of Na-4 mica layered structure•Generation of large compressive stress on the α-Fe2O3 nanfilms due to mismatch of thermal expansion coefficients of α-Fe2O3 and Na-4 mica•Observation of Piezomagnetic effect in α-Fe2O3 by changing the measurement temperature•The average values of Piezomagnetic constants extracted are in the range 2.3×10−6 to 3.4×10−4emu/gkg/cm2