Structural characterization and magnetic properties of single‐crystalline (La0.6Pr0.4)0.67Ca0.33MnO3 nanowires

Abstract

AbstractHerein, structural and magnetic properties of single‐crystalline (La0.6Pr0.4)0.67Ca0.33MnO3 nanowires synthesized via a hydrothermal process are reported. The nanowires are crystallized in an orthorhombic structure (Pnma space group). Their lattice parameters follow the relationship a ≈ c ≈ b/√2 These nanowires exhibited a clean and smooth surface with diameters of 60‐120 nm and an average length of approximately 2.0 μm. High‐resolution transmission electron microscopy images confirmed the single‐crystalline nature of the nanowires growing along the [100] direction. The nanowires demonstrated magnetic hysteresis loops at low temperatures and a weak exchange bias (EB) effect. Paramagnetic (PM)–ferromagnetic (FM) phase transition occurred at a Curie temperature (TC) of 224 K, and strong irreversibility between zero‐field‐cooled (ZFC) and field‐cooled (FC) magnetization (MZFC and MFC, respectively) curves was observed at 273 K. The MZFC curve exhibited a significantly broad peak with a maximum at a freezing temperature (Tf) of 134 K. Relative difference between MFC and MZFC in the nanowires [(MFC − MZFC)/MFC] rapidly increased below Tf and reached approximately 50% below 35 K. The effective magnetic moment deduced from the Curie constant is larger than the theoretical value, indicating short‐range FM interactions in the nanowires. A positive PM TC (θp) implies dominant FM interactions in the nanowires, and θp > TC observed herein indicates the existence of short‐range ordered states above TC.