Multiferroic nanoscale thin film materials, method of its facile syntheses and magnetoelectric coupling at room temperature

Abstract

Methods of producing a multiferroic thin film material. The method includes the steps of providing a multiferroic precursor solution, subjecting the precursor solution to spin casting to produce a spin cast film, and heating the spin cast film. The precursor solution may include Bi(NO 3 ) 3 .5H 2 O and Fe(NO 3 ) 3 .9H 2 O in ethylene glycol to produce a bismuth ferrite film. Further, the thin film may be utilized in varied technological areas, including memory devices for information storage.

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         19 . A multiferroic thin film material produced by the following steps:
 a. providing a precursor solution;   b. spin casting the precursor solution;   c. heating the spin cast precursor solution to form a multiferroic film;   d. forming the film in a perovskite structure having atoms located at B-sites in the perovskite structure;   e. substituting magnetic metal atoms having a higher valency than for the atoms located at the B-sites in the perovskite structure, to maintain neutrality and insulation of the film; and   f. wherein the film exhibits a substantially uniform arrangement of nanocrystals capable of magnetoelectric coupling at room temperature.   
     
     
         20 . The film material of  claim 19 , wherein the precursor solution includes a Bismuth solution and Iron Nitrate solution. 
     
     
         21 . The film material of  claim 20 , wherein the Bismuth solution and the Iron Nitrate solution react during heating to form a multiferroic Bismuth Ferrite (BiFeO 3 ) film. 
     
     
         22 . The film material of  claim 21 , wherein the film nanocrystals are BiFeO 3  nanocrystals having Fe atoms at the B-sites in the perovskite structure. 
     
     
         23 . The film material of  claim 22 , wherein the magnetic metal atoms having a higher valency than Fe are substituted for the Fe atoms at the B-sites at the perovskite structure, to maintain neutrality and insulation of the BiFeO 3  film. 
     
     
         24 . The film material of  claim 23 , wherein the BiFeO 3  film exhibits a substantially uniformly arrangement of BiFeO 3  nanocrystals capable of electromagnetic coupling at room temperature. 
     
     
         25 . The film material of  claim 21 , wherein the solution comprises Bi(NO 3 ) 3 .5H 2 O and Fe(NO 3 ) 3 .9H 2 O, respectively. 
     
     
         26 . The film material of  claim 25 , wherein the Bi(NO 3 ) 3 .5H 2 O and Fe(NO 3 ) 3 .9H 2 O are present in a 1:1 molar ratio. 
     
     
         27 . The film material of  claim 25 , wherein the Bi(NO 3 ) 3 .5H 2 O and Fe(NO 3 ) 3 .9H 2 O are dissolved in ethylene glycol. 
     
     
         28 . The film material of  claim 19 , wherein the spin cast precursor solution is heated in step (c) to about 600° C. 
     
     
         29 . The film material of  claim 19 , wherein the nanocrystals are about 200 nm in diameter and about 45 nm in height. 
     
     
         30 . The film material of  claim 19 , wherein the nanocrystals are subject to magnetic field induced electric polarization at room temperature. 
     
     
         31 . The film material of  claim 30 , wherein the ferromagnetic polarization of the nanocrystals is regulatable in response to an applied electrical field. 
     
     
         32 . The film material of  claim 31 , wherein the nanocrystals are subject to electrical field control of the ferromagnetic polarization of the nanocrystals. 
     
     
         33 . The film material of  claim 31 , wherein the ferromagnetic characteristics of the nanocrystals are subject to electrical field control, and electrical field characteristics of the nanocrystals are subject to magnetic field control. 
     
     
         34 . The film material of  claim 19 , wherein the electrical field characteristics of the nanocrystals are subject to magnetic field control. 
     
     
         35 . The film material of  claim 19 , wherein the magnetic field characteristics of the nanocrystals are subject to electrical field control. 
     
     
         36 . The film material of  claim 19 , wherein the nanocrystals are subject to magnetic field induced electric polarization of the nanocrystals, at room temperature. 
     
     
         37 . The film material of  claim 19 , wherein the higher valency magnetic metal atoms are substituted for about 1% to about 30% of the atoms located at the B-sites. 
     
     
         38 . The film material of  claim 19 , wherein the higher valency magnetic metal atoms are selected from the group consisting of V, Nb, Ta, W, Ti, Zr, and Hf. 
     
     
         39 . A memory device comprising the multiferroic thin film material of  claim 19 . 
     
     
         40 . The memory device of  claim 39 , wherein about 1% to about 10% of the atoms located at B-sites are substituted with magnetic metal atoms. 
     
     
         41 . The memory device of  claim 39 , wherein about 1% to about 30% of the atoms located at B-sites are substituted with magnetic metal atoms having a higher valency than Fe. 
     
     
         42 . The memory device of  claim 39 , wherein the magnetic metal atoms are selected from the group consisting of Mn, Ru, Co, and Ni. 
     
     
         43 . The memory device of  claim 39 , wherein the magnetic metal atom is at least one atom selected from the group consisting of V, Nb, Ta, W, Ti, Zr, and Hf.