Magnetic and optical properties of Fe doped crednerite CuMnO₂

Abstract

A geometrically frustrated magnetic CuMnO 2 system has been investigated because of its rich magnetic properties. Neutron diffraction, synchrotron X-ray, magnetic, X-ray photoemission spectroscopy (XPS) and UV-Visible spectroscopy measurements have been carried out on CuMnO 2 and 5% Fe doped CuMnO 2 samples. Fe doping reduces the distortion. Moreover, Fe doping induces the ferromagnetic coupling between ab planes. The value of magnetization is increased with Fe doping but coercivity is decreased. These might be due to the direct Mn-Mn exchange and Mn-O-Cu-O-Mn super-super exchange interactions. The UV-Vis data indicate the appearance of new energy bands in these compounds. The XPS study indicates that Fe is in the 3+ state.

The effect of phase transition of crednerite/delafossite CuMn1−xCrxO2 on optical, thermal, and power factor properties

“…The results confirmed that the mixed Mn 3+ /Mn 4+ ions states existed in CuMn 1−x Cr x O 2 (0 ≤ x ≤ 0.8) samples, which indicated that the Jahn-Teller distortion effect occurred on the structure. 13 In fact, the Jahn-Teller distortion behavior was decreased with increasing x content.…”

“…The distorted structure in turn caused lattice instability, which is a Jahn-Teller distortion called the Jahn-Teller effect. 12,13 The valence of Mn in the CuMnO 2 structure potentially displays M 3+ ions, while the existence of Mn 4+ ions in the nonstoichiometric Cu 1+x Mn 1−x O 2 structure displayed the formation of mixed Mn 3+ /Mn 4+ ions for stabling electrical neutrality in the structure. 14 The mixed-valent Mn 4+ /Mn 3+ state contributed to the Jahn-Teller effect following the Hund's rule, by coupling between the e g electrons on Mn 4+ ions and the t 2g core electrons on Mn 3+ ions.…”

“…14 The mixed-valent Mn 4+ /Mn 3+ state contributed to the Jahn-Teller effect following the Hund's rule, by coupling between the e g electrons on Mn 4+ ions and the t 2g core electrons on Mn 3+ ions. 13,15 The mixed states can support the charge transferring from the e g state on Mn 4+ F I G U R E 1 The schematic structures of (A) the delafossite CuCrO 2 and (B) the crednerite CuMnO 2 . The orange, purple, blue and red balls represent Cu, Mn, Cr, and O atoms, respectively ions to the t 2g states on Mn 3+ ions.…”

“…The mixture of the Fe 3+ with ionic radii (𝑟 Fe3+ ) = 0.645 Å and Mn 3+ with ionic radii (𝑟 Mn3+ ) = 0.66 Å for the CuMnFeO 2 delafossite compound became possible. 17 Regarding the magnetic and optical properties, Shukla et al 18 have studied the doped Fe 3+ on Mn substitution for CuMn 1−x Fe x O 2 compound and investigated the effect of the phase transition of the monoclinic CuMnO 2 on optical property. This effect reduced the distortion, induced the ferromagnetic coupling of ab planes, and produced new energy bands in the CuMn 1−x Fe x O 2 compounds.…”

Complementary SEM-AFM of Swelling Bi-Fe-O Film on HOPG Substrate

“…After the etching of the film, this peak appears as a part of the shoulder at 531-532 eV. The spectra shoulders around 531 eV refer to excess oxygen (marked as O − ) [37]. The incorporated nitro (532.7 eV) [38] and hydroxyl (533 eV) [39] groups cause a shift in O1s and are responsible for the high-energy shoulder.…”