Magnetic, thermodynamic, and electrical transport properties of the noncentrosymmetric B20 germanides MnGe and CoGe

Abstract

We present magnetization, specific heat, resistivity, and Hall effect measurements on the cubic B20 phase of MnGe and CoGe and compare to measurements of isostructural FeGe and electronic structure calculations. In MnGe, we observe a transition to a magnetic state at $T_c=275$ K as identified by a sharp peak in the ac magnetic susceptibility, as well as second phase transition at lower temperature that becomes apparent only at finite magnetic field. We discover two phase transitions in the specific heat at temperatures much below the Curie temperature one of which we associate with changes to the magnetic structure. A magnetic field reduces the temperature of this transition which corresponds closely to the sharp peak observed in the ac susceptibility at fields above 5 kOe. The second of these transitions is not affected by the application of field and has no signature in the magnetic properties or our crystal structure parameters. Transport measurements indicate that MnGe is metal with a negative magnetoresistance similar to that seen in isostructural FeGe and MnSi. Hall effect measurements reveal a carrier concentration of about 0.5 carriers per formula unit also similar to that found in FeGe and MnSi. CoGe is shown to be a low carrier density metal with a very small, nearly temperature independent diamagnetic susceptibility.

arXiv comment16 pages 23 figures

References in corpus (14)

• Skyrmion Lattice in a Chiral Magnet
• Topological Hall effect in the A-phase of MnSi
• Skyrmion Lattice in a Doped Semiconductor
• Precursor phenomena at the magnetic ordering of the cubic helimagnet FeGe
• Large Anomalous Hall effect in a silicon-based magnetic semiconductor
• Magnetoresistance From Quantum Interference Effects in Ferromagnets
• A hidden constant in the anomalous Hall effect of a high-purity magnet MnSi
• Implications of the B20 Crystal Structure for the Magneto-electronic Structure of MnSi
• Confinement of Chiral Magnetic Modulations in the Precursor Region of FeGe
• Spin, Charge, and Bonding in Transition Metal Mono Silicides
• Metal-insulator transition and magnetism in correlated band insulator: FeSi and Fe${}_{1-x}$Co${}_x$Si
• First-order transition between a small-gap semiconductor and a ferromagnetic metal in the isoelectronic alloys FeSi${}_{1-x}$Ge${}_x$
• First order transition from correlated electron semiconductor to ferromagnetic metal in single crystalline FeSi1-xGex
• Electronic structure and magnetism for FeSi${}_{(1-x)}$Ge${}_x$ from supercell calculations

Cited by in corpus (20)

• Dzyaloshinskii-Moriya interaction and Hall effects in the skyrmion phase of MnFeGe alloys
• Transferability of neural network potentials for varying stoichiometry: phonons and thermal conductivity of Mn${}_x$Ge${}_y$ compounds
• Scaling Study and Thermodynamic Properties of the cubic Helimagnet FeGe
• Effect of Negative Pressure on the Prototypical Itinerant Magnet MnSi
• Fermi surface, possible unconventional fermions, and unusually robust resistive critical fields in the chiral-structured superconductor AuBe
• Exploring the origins of the Dzyalloshinski-Moria interaction in MnSi
• Complex magnetism of B20-MnGe: from spin-spirals, hedgehogs to monopoles
• Magnetic, electronic and transport properties of high-pressure-synthesized chiralmagnets Mn${}_{1-x}$Rh${}_x$Ge (B20)
• Fragile balance of the exchange interactions in Mn${}_{1-x}$Co${}_x$Ge compounds
• Theoretical and experimental study of high-pressure synthesized B20-type compounds Mn${}_{1-x}$(Co,Rh)${}_x$Ge
• Thermoelectric and optical probes for a Fermi surface topology change in noncentrosymmetric metals
• Thermal expansion and compressibility of monogermanides of 3d-metals
• Electronic and dynamical properties of cobalt monogermanide CoGe phases under pressure
• Possible quadrupole-order-driven commensurate-incommensurate phase transition in B20 CoGe
• Ab initio study of noncentrosymmetric transition-metal monogermanide B20-RhGe synthesized at high temperature and pressure
• Direct observations of spin fluctuations in spin-hedgehog-anti-hedgehog lattice states in MnSi${}_{1-x}$Ge${}_x$ ($x=0.6$ and $0.8$) at zero magnetic field
• Zero-energy Bound States in Nodal Topological Lattice
• Physical properties of RhGe and CoGe single crystals synthesized under high pressure
• First-principles study of magnetic interactions in FeGe
• Low magnetic moment and unconventional magneto-transport in half-Heusler alloy CoVGe