R&D: Magneto-Electric Coupled Ordered PMN-PT/NiFe2O4 Composite Nanostructures

Applied Physics Letters has published an article written by Anju Ahlawat, UGC-DAE Consortium for Scientific Research, Indore, India, Robert Roth, Diana Rata, Kathrin Dorr, Institute of Physics, Martin Luther University Halle-Wittenberg, 06099 Halle, Germany, Azam Ali Khan, Pratik Deshmukh, Laser and Functional Materials Division, Raja Ramanna Centre for Advanced Technology, Indore 452013, India, and HomiBhabha National Institute, Training School Complex, Anushakti Nagar, Mumbai 400094, India, Mandar M. Shirolkar, Symbiosis Center for Nanoscience and Nanotechnology (SCNN), Symbiosis International (Deemed University) (SIU), Lavale, Pune 412115, Maharashtra, India, S. Satapathy, Laser and Functional Materials Division, Raja Ramanna Centre for Advanced Technology, Indore 452013, India, and HomiBhabha National Institute, Training School Complex, Anushakti Nagar, Mumbai 400094, India, R. J. Choudhary, and D. M. Phase, UGC-DAE Consortium for Scientific Research, Indore, India.

Abstract: “In this work, a well-ordered array of multiferroic magnetoelectric (ME) dot-like nanostructures of Pb(Mg_1/3Nb_2/3)O₃]_0.65–[PbTiO₃]_0.35 (PMN-PT)/NiFe₂O₄ is explored for high density and low power consuming memory devices. Ordered arrays of ferromagnetic NiFe₂O₄ nanodots underneath a ferroelectric PMN-PT layer were fabricated using silicon nitride based stencil masks and pulsed laser deposition techniques. The piezo-response and magnetic force microscopy (PFM) measurements reveal coexistence of magnetic and ferroelectric domains in PMN-PT/NiFe₂O₄ films at room temperature. The ferroelectric polarization can be switched with the electrically biased PFM tip. The ME coupling is evident in the PMN-PT/NiFe₂O₄ films, which is attributed to the transfer of the elastic strain from PMN-PT to NiFe₂O₄. The PMN-PT/NiFe₂O₄ nanodot films exhibit enhanced ME coupling coefficient (α) as compared to continuous bilayer PMN-PT/NiFe₂O₄ films, owing to the superior strain transfer efficiency in nanodot heterostructures. The nanodot films demonstrate electric-field controlled nonvolatile switching of α, which can be used to store binary information in memory devices, holding all the advantages of ferroelectric random access memory but overcoming the major disadvantage of destructive reading of polarization. The results reveal a versatile approach for fabrication of well-ordered nanodot arrays for low power consuming, high-density ME device applications.“

The authors would like to acknowledge Mr. Rakesh Kumar Sah and Mr. Avinash Wadikar for help in the XMCD measurements. The authors also thank CSIR, New Delhi for the financial support.