Dicalcium ruthenate, with the chemical formula Ca₂RuO₄, is a stochiometric

oxide An oxide () is a chemical compound containing at least one oxygen atom and one other element in its chemical formula. "Oxide" itself is the dianion (anion bearing a net charge of −2) of oxygen, an O2− ion with oxygen in the oxidation st ...

compound that hosts a multi-orbital (band) Mott insulating ground state. For this reason, Ca₂RuO₄ serves as an important "meeting-point" between conceptual developments of strongly correlated multi-band physics and advanced experimental spectroscopies. Its electronic structure and also orbital

magnetism Magnetism is the class of physical attributes that occur through a magnetic field, which allows objects to attract or repel each other. Because both electric currents and magnetic moments of elementary particles give rise to a magnetic field, ...

are therefore subjects of experimental and theoretical scrutiny.

Electronic properties

Around 350 K, Ca₂RuO₄ undergoes a metal insulator transition which involves a crystal structure transition leading to a strong ''c''-axis compression. Negative thermal expansion has also been reported in conjunction with this ''c''-axis compression. The metal insulator transition is sensitive to electrical current. Below 80 K, an anti-ferromagnetic ordering emerges.

Related materials

Ca_1.8Sr_0.2RuO₄ has been proposed as a candidate system for orbital selective Mott physics. The bilayer compound Ca₃Ru₂O₇ is metallic, but display a sequence of electronic transitions below 60 K. Finally, Sr₂RuO₄ hosts an unconventional superconducting state.

References

{{physics-stub Calcium compounds Ruthenates Condensed matter physics