Itinerant G-type antiferromagnet SrCr2As2 studied by magnetization, heat capacity, electrical resistivity, and NMR measurements

Abstract

The physical properties of itinerant antiferromagnetic (AFM) SrCr${}_2$As${}_2$ with body-centered tetragonal ThCr${}_2$Si${}_2$ structure were investigated in single crystalline and polycrystalline forms by electrical resistivity $\rho$, heat capacity $C_{\mathrm{p}}$, magnetic susceptibility $\chi$ versus temperature~$T$ and magnetization $M$ versus applied magnetic field $H$ isotherm measurements as well as ${}^{75}$As and ${}^{53}$Cr nuclear magnetic resonance (NMR) measurements in the wide temperature range $T$ = 1.6--900 K. From the $\chi (T)$ and ${}^{75}$As NMR measurements, the G-type AFM state below $T_{\mathrm{N}}$ = 615(15) K has been determined, consistent with the previous neutron-diffraction measurements. Direct evidence of magnetic ordering of the Cr spins was shown by the observation of the ${}^{53}$Cr NMR spectrum under $H$ = 0. From the $\chi (T)$ measurements on single-crystal SrCr${}_2$As${}_2$ under the two different magnetic field directions $H||ab$ and $H||c$ in the AFM state, the Cr ordered moments are shown to align along the $c$ axis in the G-type AFM state. The metallic state is directly evidenced by the $\rho$, $C_{\mathrm{p}}$, and NMR measurements, and the density of states at the Fermi energy $\mathcal{D}(E_{\mathrm{F}})$ in the AFM state is estimated to be 7.53 states/eV f.u. for both spin directions which is almost twice the bare $\mathcal{D}(E_{\mathrm{F}})$ estimated from first-principles calculations, suggesting an enhancement of the conduction-carrier mass by a factor of two in the AFM state. The $\mathcal{D}(E_{\mathrm{F}})$ is found to be nearly constant below at least 100 K and is independent of $H$. The $\rho (T)$ is found to show $T$-linear behavior above $T_{\mathrm{N}}$ and exhibits positive curvature below $T_{\mathrm{N}}$ where significant loss of spin-disorder scattering upon magnetic ordering is observed.

14 pages, 12 figures, accepted for publication in Phys. Rev. B

References in corpus (13)

• Superconductivity in the vicinity of antiferromagnetic order in CrAs
• Commensurate Itinerant Antiferromagnetism in BaFe2As2: 75As-NMR Studies on a Self-Flux Grown Single Crystal
• Superconductivity in quasi-one-dimensional K${}_2$Cr${}_3$As${}_3$ with significant electron correlations
• Anisotropy of the Optimally-Doped Iron Pnictide Superconductor Ba(Fe0.926Co0.074)2As2
• Unconventional superconductivity in quasi-one-dimensional Rb${}_2$Cr${}_3$As${}_3$
• Superconductivity in quasi-one-dimensional Cs2Cr3As3 with large interchain distance
• Superconductivity of 2.2 K under Pressure in Helimagnet CrAs
• Itinerant antiferromagnetism in BaCr${}_2$As${}_2$
• Itinerant and local-moment magnetism in EuCr2As2 single crystals
• Antiferromagnetism in semiconducting SrMn2Sb2 and BaMn2Sb2 single crystals
• Strong correlations and the search for high-Tc superconductivity in chromium pnictides and chalcogenides
• Itinerant G-type antiferromagnetic order in SrCr${}_2$As${}_2$
• Breaking the ring: ${}^{53}$Cr-NMR on the Cr${}_8$Cd molecular nanomagnet