Transport and Magnetic Studies on the Spin State Transition of Pr1-xCaxCoO3 up to High Pressure

Toshiaki Fujita; Takeshi Miyashita; Yukio Yasui; Yoshiaki Kobayashi; Masatoshi Sato; Eiji Nishibori; Makoto Sakata; Yutaka Shimojo; Naoki Igawa; Yoshinobu Ishii; Kazuhisa Kakurai; Takafumi Adachi; Yasuo Ohishi; Masaki Takata

doi:10.1143/jpsj.73.1987

arXiv · cond-mat/0402517

Transport and Magnetic Studies on the Spin State Transition of Pr1-xCaxCoO3 up to High Pressure

Toshiaki Fujita·Takeshi Miyashita·Yukio Yasui·Yoshiaki Kobayashi·Masatoshi Sato·Eiji Nishibori·Makoto Sakata·Yutaka Shimojo·Naoki Igawa·Yoshinobu Ishii·Kazuhisa Kakurai·Takafumi Adachi·Yasuo Ohishi·Masaki Takata

View original source ↗Read source document ↗Export metadata ↓

Abstract

Transport and magnetic measurements and structural and NMR studies have been carried out on (Pr1-yR'y)1-xAxCoO3 {R'=(rare earth elements and Y); A=(Ca, Ba and Sr)} at ambient pressure or under high pressure. The system exhibits a phase transition from a nearly metallic to an insulating state with decreasing temperature T, where the low spin (LS) state of Co3+ is suddenly stabilized. For y=0, we have constructed a T-x phase diagram at various values of the external pressure p. It shows that the (T, x) region of the low temperature phase, which is confined to a very narrow region around x=0.5 at ambient pressure, expands as p increases, suggesting that the transition is not due to an order-disorder type one. For the occurrence of the transition, both the Pr and Ca atoms seem to be necessary. The intimate relationship between the local structure around the Co ions and the electronic (or spin) state of Co3+ ions is discussed: For the smaller unit cell volume or the smaller volume of the CoO6 octahedra and for the larger tilting angle of the octahedra, the temperature of the transition becomes higher. The role of the carriers introduced by the doping of the A atoms, is also discussed. By analyzing the data of 59Co-NMR spectra and magnetic susceptibilities of Pr1-xCaxCoO3 the energy separations among the different spin states of Co3+ and Co4+ are roughly estimated.

Explore related subjects

cond-mat.str-el cond-mat.mtrl-sci

Keep this discovery

Explore connections, maps & timelines

BibTeX RIS

Toshiaki Fujita, Takeshi Miyashita, Yukio Yasui, Yoshiaki Kobayashi, Masatoshi Sato, Eiji Nishibori, Makoto Sakata, Yutaka Shimojo, Naoki Igawa, Yoshinobu Ishii, Kazuhisa Kakurai, Takafumi Adachi, Yasuo Ohishi, Masaki Takata. 2004-02-21. Transport and Magnetic Studies on the Spin State Transition of Pr1-xCaxCoO3 up to High Pressure. https://doi.org/10.1143/jpsj.73.1987

Cite the original work for its findings. Save a collection to share your selection of sources.

KEEP EXPLORING

Related papers

arXiv2026

An Atlas of Classical Pyrochlore Spin Liquids

Frustrated magnetism in the pyrochlore lattice magnet has proven to be a most fruitful setting for the experimental and theoretical search for spin liquids. Besides the canonical case of spin ice, recent works have identified a variety of new classical and quantum spin liquids engendered by the generic nearest-neighbor anisotropic spin Hamiltonian for that lattice. However, a general framework for the thorough and systematic classification and characterization of these exotic states of matter has been lacking, as has an exhaustive list of all possible spin liquids that this model can support and, perhaps most interesting, what is the corresponding structure of their emergent field theory description. In this work, we develop such a theoretical framework to identify the interaction parameters stabilizing different classical spin liquids and derive their corresponding effective generalized Gauss's laws at low temperatures. Combining this with Monte Carlo simulations, we systematically identify all classical spin liquids for the general nearest-neighbor anisotropic spin Hamiltonian on the pyrochlore lattice. In doing so, we uncover new spin liquid models with exotic forms of generalized Gauss's law and multipole conservation laws. Our approach allows us to compile an atlas of all spin liquids realized in the phase diagram, providing a global picture of their mutual connections in parameter space and transitions between them. Our work will inform future theoretical and experimental studies of classical and quantum spin liquids on the pyrochlore lattice and help rationalize the exotic properties of pyrochlore magnets.

cond-mat.str-el↗

arXiv2026

Spectroscopic Evidence of Competing Diagonal Spin Interactions and Spin Disproportionation in the Bilayer Nickelate La$_3$Ni$_2$O$_7$

A comprehensive spectroscopic map of the electronic, magnetic, and lattice excitations is presented for the bilayer nickelate La$_3$Ni$_2$O$_7$ using Raman scattering at ambient pressure. Upon entering the spin density wave state below 153 K, the $A_{1g}$ channel exhibits an abrupt electronic spectral gap with a clear isosbestic point. In contrast, the $B_{1g}$ and $B_{2g}$ channels are dominated by pronounced two-magnon (2M) excitations, representing a signature of incipient Mottness. These 2M signals in both channels constitute evidence for two distinct in-plane spin exchange interactions along the Ni-O bonding and its diagonal directions. Calculations based on the spin wave theory further reveal that the 2M mode in the $B_{2g}$ channel arises from the competition between two bond-diagonal antiferromagnetic interactions mediated by nickel $d_{x^2-y^2}$ orbitals. Furthermore, emergent low-energy 2M excitations below 10 meV are found to originate from distinct, weaker spin moments, supporting spin disproportionation. Simultaneously, an anomalous softening of $B_{1g}$ phonons from 280 down to 4.5 K is uncovered, suggesting the presence of an incipient lattice instability leading to checkerboard-type breathing modulations. Collectively, these findings identify a ground state of the bilayer nickelate characterized by competing bond-diagonal interactions, spin disproportionation, and an incipient lattice instability, establishing key ingredients for understanding the mechanism of nickelate superconductivity.

cond-mat.str-el↗

arXiv2026

Direction-selective intertwined charge, orbital, and lattice orders under uniaxial strain in hole-doped manganite: La0.75Ca0.25MnO3

The complex interplay of charge, spin, orbital, and lattice degrees of freedom governs emergent phases in quantum materials, making strain a powerful control parameter. Recent advances in free-standing layer techniques have enabled extreme strains of nearly 8%, opening access to novel and often unexpected electronic and magnetic phases. Here, using a density functional theory approach, we investigate the effect of direction-selective uniaxial strain on the prototypical Jahn-Teller system La1-xCaxMnO3 (x = 0.25). We find that different strain directions stabilize qualitatively distinct structural, charge, and orbital responses, rather than merely different strengths of the same phase. In particular, extreme uniaxial strain selectively induces cooperative Jahn-Teller, breathing-like, and site-selective modulations, thereby enabling previously inaccessible intertwined orders in manganites. These results establish direction-selective uniaxial strain as a powerful and selective route for engineering emergent phases in quantum materials.

cond-mat.str-el↗