[1] [1] RAMESH R, SPALDIN N A. Multiferroics: progress and prospects in thin films［J］. Nature Materials, 2007, 6(1): 21-29.

[2] [2] TOKURA Y. Materials science. multiferroics as quantum electromagnets［J］. Science, 2006, 312(5779): 1481-1482.

[3] [3] YOO Y J, HWANG J S, LEE Y P, et al. High ferromagnetic transition temperature in multiferroic BiFe0.95Ni0.05O3 compound［J］. Journal of Applied Physics, 2013, 114(16): 163902.

[4] [4] MAZUMDAR S, DATTA S, ALAM F. Structural, magnetic and transport properties of Gd and Cu Co-doped BiFeO3 multiferroics［J］. Journal of Applied Mathematics and Physics, 2022, 10(006): 2026-2039.

[5] [5] JHA V K, SIJO A K, ALAM S N, et al. Effect of Nd doping on structural, electrical, thermal and magnetic properties of multifunctional BiFeO3 ceramics［J］. Journal of Superconductivity and Novel Magnetism, 2020, 33(2): 455-461.

[6] [6] DURGA RAO T, RAJA KANDULA K, KUMAR A, et al. Improved magnetization and reduced leakage current in Sm and Sc co-substituted BiFeO3［J］. Journal of Applied Physics, 2018, 123(24): 244104.

[7] [7] SONG S H, ZHU Q S, WENG L Q, et al. A comparative study of dielectric, ferroelectric and magnetic properties of BiFeO3 multiferroic ceramics synthesized by conventional and spark plasma sintering techniques［J］. Journal of the European Ceramic Society, 2015, 35(1): 131-138.

[8] [8] SPALDIN N A. Multiferroics: past, present, and future［J］. MRS Bulletin, 2017, 42(5): 385-390.

[9] [9] SHI X, LIU X, CHEN X. Readdressing of magnetoelectric effect in bulk BiFeO3 ［J］. Advanced Functional Materials, 2017, 27(12):1604037.1-1604037.9.

[10] [10] DAS R, KHAN G G, MANDAL K. Enhanced ferroelectric, magnetoelectric, and magnetic properties in Pr and Cr co-doped BiFeO3 nanotubes fabricated by template assisted route［J］. Journal of Applied Physics, 2012, 111(10): 104115.

[11] [11] YUAN G L, OR S W. Multiferroicity in polarized single-phase Bi0.875Sm0.125FeO3 ceramics［J］. Journal of Applied Physics, 2006, 100(2): 024109.

[12] [12] ZHANG S X, WANG L, CHEN Y, et al. Observation of room temperature saturated ferroelectric polarization in Dy substituted BiFeO3 ceramics［J］. Journal of Applied Physics, 2012, 111(7): 074105.

[13] [13] YUAN G L, OR S W. Enhanced piezoelectric and pyroelectric effects in single-phase multiferroic Bi1-xNdxFeO3 (x=0~0.15) ceramics［J］. Applied Physics Letters, 2006, 88(6): 062905.

[14] [14] JEON N, ROUT D, KIM I W, et al. Enhanced multiferroic properties of single-phase BiFeO3 bulk ceramics by Ho doping［J］. Applied Physics Letters, 2011, 98(7): 072901.

[15] [15] GUO R Q, FANG L, DONG W, et al. Enhanced photocatalytic activity and ferromagnetism in Gd doped BiFeO3 nanoparticles［J］. The Journal of Physical Chemistry C, 2010, 114(49): 21390-21396.

[16] [16] PAPI H D, AHMADVAND H, SHAHBAZ M T, et al. Dielectric and magnetoelectric properties of (BiBa)(FeTiZn)O3/CoFe2O4 lead-free particulate composites［J］. Journal of Magnetism and Magnetic Materials, 2021, 521: 167484.

[17] [17] WU J G, FAN Z, XIAO D Q, et al. Multiferroic bismuth ferrite-based materials for multifunctional applications: ceramic bulks, thin films and nanostructures［J］. Progress in Materials Science, 2016, 84: 335-402.

[18] [18] ABLAT A, WU R, MAMAT M, et al. Structural analysis and magnetic properties of Gd doped BiFeO3 ceramics［J］. Ceramics International, 2014, 40(9): 14083-14089.

[19] [19] KUMAR M, CHANDRA SATI P, CHHOKER S, et al. Electron spin resonance studies and improved magnetic properties of Gd substituted BiFeO3 ceramics［J］. Ceramics International, 2015, 41(1): 777-786.

[20] [20] WEI J, LIU Y, BAI X F, et al. Crystal structure, leakage conduction mechanism evolution and enhanced multiferroic properties in Y-doped BiFeO3 ceramics［J］. Ceramics International, 2016, 42(12): 13395-13403.

[21] [21] IAKOVLEV S, SOLTERBECK C H, KUHNKE M, et al. Multiferroic BiFeO3 thin films processed via chemical solution deposition: structural and electrical characterization［J］. Journal of Applied Physics, 2005, 97(9): 094901.

[22] [22] PABST G W, MARTIN L W, CHU Y H, et al. Leakage mechanisms in BiFeO3 thin films［J］. Applied Physics Letters, 2007, 90(7): 072902.

[23] [23] PRADHANI N, MAHAPATRA P K, CHOUDHARY R N P. Structural, impedance, and leakage current characteristics of stannum modified Bi0.5Na0.5TiO3 ceramic［J］. Journal of Inorganic and Organometallic Polymers and Materials, 2021, 31(2): 591-598.

[24] [24] XUE F, TIAN Y H, JIAN G, et al. Ferroelectromagnetic pseudocubic BiFeO3-LaFeO3-PbFeO2.5: leakage current, dielectric, and multiferroic properties at room temperature［J］. Ceramics International, 2020, 46(1): 930-936.

[25] [25] LUO J M, LIN S P, ZHENG Y, et al. Nonpolar resistive switching in Mn-doped BiFeO3 thin films by chemical solution deposition［J］. Applied Physics Letters, 2012, 101(6): 062902.

[26] [26] KUMAR S. Structural, dielectric and magnetic characterization of large scale template synthesized Gd doped BiFeO3 nanowires［J］. Journal of Materials Science: Materials in Electronics, 2013, 24(6): 2112-2115.