First-order magnetization process and spin phase diagram of Nd2Fe14-xGa xB and Nd2Fe11.5-xCo2.5GaxB.

Abstract

The first-order-magnetization-process (FOMP) transition field, Curie temperature, and spin-reorientation temperature of Nd{sub 2}Fe{sub 14{minus}{ital x}}Ga{sub {ital x}}B and Nd{sub 2}Fe{sub 11.5{minus}{ital x}}Co{sub 2.5}Ga{sub {ital x}}B with {ital x}{le}1.5 have been determined. Ga increases the Curie temperature of Nd{sub 2}Fe{sub 14{minus}{ital x}}Ga{sub {ital x}}B but decreases that of Nd{sub 2}Fe{sub 11.5{minus}{ital x}}Co{sub 2.5}Ga{sub {ital x}}B compounds. This difference in the behavior of Ga stems from the preferential occupancy of Fe sites being different in the above two compound series. The spin-reorientation temperature of these compounds decreased with increasing Ga content. The FOMP transition field changed in an opposite manner. At a fixed temperature (180 K), it increased with increase in Ga content. The lower the temperature, the more pronounced the increase of the FOMP transition field {ital B}{sub tr}. Based on these findings, spin phase diagrams were constructed.