(a) Magnetization-temperature (MT) curves of BaFeO3 measured with applied field (H) of 1 kOe. FC and ZFC stand for field-cooled and zero-field-cooled modes, respectively. The inset shows the derivative of M against T to demonstrate T C ∼ 110 K. (b) Inverse magnetization (1/M) plotted against T, obtained from Fig. 1(a) . Exp stands for the experimental data. Curie-Weiss fit is shown by a blue line. (c) MT curves measured with some various applied fields in the FC mode. The measurements were carried out while cooling the sample (FCC) except where noted. For the fields of 0.5 kOe and 50 kOe, the results obtained in the heating process (FCH) are shown. The details of both processes are given in the text.
Isothermal magnetization-magnetic field (MH) curve at 4.5 K. The low-field region (inset) shows small magnetic coercivity.
(a) Isothermal magnetization-magnetic field (MH) curves at several representative temperatures in the refrigeration temperature range near T C. The processes of increasing and decreasing in the applied field (H) are denoted as (i) and (d), respectively. The data (i) were used to obtain the Arrott plot (Fig. 3(b) ) and the entropy change (Fig. 4(a) ). More details arenoted in the text. (b) Arrott plot at several representative temperatures in the refrigeration temperature range. The data are obtained from the MH curves in Fig. 3(a) .
(a) Negative value of the change in magnetic entropy (−ΔS) plotted against T, calculated from the MH data (Fig. 3(a) ). T 1 and T 2 stand for the refrigeration temperature range for the applied field (H) of 50 kOe (Eq. (1) ). (b) Refrigerant capacity (RC) plotted against several applied fields (H; Eq. (1) ) between 10 and 50 kOe. Each RC value was calculated by the integration of −ΔS between T 1 and T 2 for each H in Fig. 4(a) . The solid line is a guide for eye.
Magnetic circular dichroism (MCD) spectrum at the Fe-L 3,2 edges for BaFeO3 at 15 K, obtained by X-ray absorption spectroscopy (XAS). Red (I +) and green (I −) circles show the XAS spectra measured with an external field of 19 kOe parallel and antiparallel to the light propagation axis, respectively. The bottom line represents the MCD intensity I MCD, obtained from the absorption spectra (IMCD = I− − I +). The arbitrary unit of intensity in the XAS spectrum was set to unity at 737 eV.
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