Electrical, magnetic, and magnetoresistance studies in chromium-doped Pr-based manganites

• Published in: JOURNAL OF MATERIALS SCIENCE-MATERIALS IN ELECTRONICS
• Main Authors: Sumaiyah, S.; Ibrahim, N.; Mohamed, Z.; Rozilah, R.; Kazmi, Jamal; Masood, Asad; Ali, Muhammed
• Format: Article
• Language: English
• Published: SPRINGER 2024
• Subjects: Engineering; Materials Science; Physics
• Online Access: https://www-webofscience-com.uitm.idm.oclc.org/wos/woscc/full-record/WOS:001263129300003

The effect of Cr3+ on the electrical, magnetic and magnetoresistance effect in Pr0.75Na0.05K0.2Mn1-xCrxO3 (x = 0.0, 0.01, 0.02, 0.03, 0.04, 0.05) synthesised using the solid-state method are reported. An analysis at room temperature of X-ray diffraction data using the Rietveld refinement method showed all samples crystallised in the orthorhombic phase with Pnma space group. It is found that unit cell volume increased from 230.60 & Aring;3 (x = 0) to 231.25 & Aring;3 (x = 0.01) suggesting that substitution with a low concentration of Cr3+ may predominately substitute for Mn4+ site. However, further substituting Cr3+ caused a decrease in unit cell volume from 231.15 & Aring;3 (x = 0.02) to 227.74 & Aring;3 (x = 0.05), indicating at high concentration of Cr3+ dominantly substituted the Mn3+. Cr3+ substitution slightly decreased the Curie temperature (TC)\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$${(T}_{C})$$\end{document} value from 140.7 K (x = 0.00) to 139.7 K (x = 0.01) and 139.3 K (x = 0.02) indicates the substitution of Cr3+ slightly disturb ferromagnetic (FM) interaction between Mn3+-O2--Mn4+. Interestingly, further substitution of Cr3+ increased the TC\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$${T}_{C}$$\end{document} to 140 K (x = 0.03), 140.7 K (x = 0.04) and 143.4 K (x = 0.05) which revealed the possibility of the existence of ferromagnetic interaction between Cr3+ and Mn3+ ions due to the similar electronic configuration of Cr3+ with that of Mn4+ ions. The observed large increased in resistivity with Cr3+ substitution and the decrease in metal insulator transition temperature (TMI) from 122 K (x = 0) to 90 K (x = 0.05) from resistivity versus temperature curve indicates the Cr substitution weakened mechanism and induce more competition between double-exchange (DE) and super-exchange (SE) mechanism involving Mn3+-O2--Mn4+, Cr3+-O2--Mn3+, Cr3+-O2--Cr3+, Cr3+-O2--Mn4+. The observation large magnetoresistance (MR) effect in Cr-substituted sample at low temperature region indicates enhancement of extrinsic MR effect, which likely arises from spin polarized tunnelling.