Elastic and electrical anomalies at low-temperature phase transitions in BiFeO₃

Abstract

Our measured dielectric constant and mechanical response of multiferroic BiFeO 3 indicate four phase transitions below room temperature. Features correlate with those reported at 50 K (from a peak in the zero-field-cooled magnetic susceptibility) and 230 K (from splitting between field-cooled and zero-field-cooled magnetic data;

Dielectric dynamics of epitaxial BiFeO3 thin films

“…They are related to the ferroelastic phase transitions at low temperature. 16 Many other literatures have connected the anomaly in capacitance with certain phase transitions. 25,[27][28][29][30][31][32][33][34][35][36][37][38][39] In the field of multiferroics, for example, the anomalies were often accompanied by antiferromagnetic transition, 27, 37, 40-42 domain formation, 43 phase transition near the morphotropic phase boundary (MPB) 44,45 and many other magnetic phase transitions.…”

“…[11][12][13][14][15] The dielectric measurements based on BFO bulk materials revealed that the elastic and dielectric anomalies at low temperature may be related to these transitions. 16 The electrical equivalent circuit fitting was utilized to investigated the impedance spectroscopy (IS) of epitaxial BFO thin films above room temperature. 6 In this paper, we present the dielectric property of epitaxial BFO below room temperature.…”

BiFeO3Crystal Structure at Low Temperatures

“…There are also changes of the Fe nuclear magnetic resonance (NMR) signal reported at RT and at 100 K [21], and anomalies of the Raman spectra near 140 K and 200 K shows that the magnetic moments' direction changes in a periodic way [3]. [22][23][24], as well as, elastic and electrical anomalies [25]. On the other hand, recent BiFeO 3 magnetic [26,27], dielectric and heat capacity [27] studies do not show any anomalies below RT.…”

Магнитоемкость тонких пленок Gd-=SUB=-x-=/SUB=-Bi-=SUB=-1-x-=/SUB=-FeO-=SUB=-3-=/SUB=-

“…4). При этих температурах в объемных образцах наблюдались максимумы в интенсивности в магнонном рамановском спектре с небольшим сдвигом частот при T 1 = 140 K и T 2 = 201 K [15], максимум в по-глощении ультразвука при T = 200 K [16] и зависимость восприимчивости от предыстории образца, охлажденно-го в поле и без поля [17]. Температура, при которой (χ FC − χ ZF ) восприимчивости отличаются, зависит от по-ля и смещается от T = 220 K в поле 0.5 kOe до T = 80 K в поле 10 kOe [17].…”