Ultra-small moment incommensurate spin density wave order masking a ferromagnetic quantum critical point in NbFe${}_2$

Abstract

In the metallic magnet Nb${}_{1-y}$Fe${}_{2+y}$, the low temperature threshold of ferromagnetism can be investigated by varying the Fe excess $y$ within a narrow homogeneity range. We use elastic neutron scattering to track the evolution of magnetic order from Fe-rich, ferromagnetic Nb${}_{0.981}$Fe${}_{2.019}$ to approximately stoichiometric NbFe${}_2$, in which we can, for the first time, characterise a long-wavelength spin density wave state burying a ferromagnetic quantum critical point. The associated ordering wavevector ${\mathbf{q}}_{\mathrm{SDW}}=$(0,0,$l_{\mathrm{SDW}}$) is found to depend significantly on $y$ and $T$, staying finite but decreasing as the ferromagnetic state is approached. The phase diagram follows a two order-parameter Landau theory, for which all the coefficients can now be determined. Our findings suggest that the emergence of SDW order cannot be attributed to band structure effects alone. They indicate a common microscopic origin of both types of magnetic order and provide strong constraints on related theoretical scenarios based on, e.g., quantum order by disorder.

arXiv commentAddition of absolute magnetic moment estimates and of a two order-parameter Landau model analysis

References in corpus (18)

• Superconducting phases of f-electron compounds
• Metallic Quantum Ferromagnets
• Quantum Phase Transitions in the Itinerant Ferromagnet ZrZn${}_2$
• Pressure induced superconductivity on the border of magnetic order in MnP
• Pressure dependence of the magnetization in the ferromagnetic superconductor UGe_2
• Nonanalytic behavior of the spin susceptibility in clean Fermi systems
• Quantum-critical behavior of itinerant ferromagnets
• Ferromagnetic quantum critical fluctuations in YbRh_2(Si_{0.95}Ge_{0.05})_2
• Field tunable spin density wave phases in Sr3Ru2O7
• Spin-fluctuation dominated electrical transport of Ni3Al at high pressure
• Tricritical wings and modulated magnetic phases in LaCrGe${}_3$ under pressure
• Quantum Tricritical Points in NbFe${}_2$
• Quantum order-by-disorder driven phase reconstruction in the vicinity of ferromagnetic quantum critical points
• From incommensurate correlations to mesoscopic spin resonance in YbRh2Si2
• Magnetism in Nb(1-y)Fe(2+y) - composition and magnetic field dependence
• Spectroscopic study of the magnetic ground state of Nb${}_{1-y}$Fe${}_{2+y}$
• Avoided ferromagnetic quantum critical point in CeRuPO
• Doping driven magnetic instabilities and quantum criticality of NbFe${}_2$

Cited by in corpus (6)

• Formation of short-range magnetic order and avoided ferromagnetic quantum criticality in pressurized LaCrGe${}_3$
• Avoided ferromagnetic quantum critical point in pressurized La${}_5$Co${}_2$Ge${}_3$
• Muon spin rotation and relaxation study on Nb${}_{1-y}$Fe${}_{2+y}$
• Field Induced Modulated State in the Ferromagnet PrPtAl
• Avoided ferromagnetic quantum critical point in CeZn
• Effect of Ni substitution on the fragile magnetic system ${\text{La}}_5{\text{Co}}_2{\text{Ge}}_3$