Ferromagnetism versus slow paramagnetic relaxation in Fe-doped
- Univ. of Augsburg (Germany). EP VI, Center for Electronic Correlations and Magnetism, Inst. of Physics
- Univ. of Augsburg (Germany). EP VI, Center for Electronic Correlations and Magnetism, Inst. of Physics; Ames Lab. and Iowa State Univ., Ames, IA (United States)
- Univ. of Augsburg (Germany). Chair of Solid State Chemistry, Inst. of Physics
- Technische Universitat Dresden, Dresden (Germany). Inst. for Solid State and Materials Physics
- Univ. of Augsburg (Germany). EP VI, Center for Electronic Correlations and Magnetism, Inst. of Physics; IIT Tirupati, Tirupati (India). Dept. of Physics
- Ames Lab. and Iowa State Univ., Ames, IA (United States); Iowa State Univ., Ames, IA (United States). Dept. of Physics and Astronomy
We report on isothermal magnetization, Mössbauer spectroscopy, and magnetostriction as well as temperature-dependent alternating-current (ac) susceptibility, specific heat, and thermal expansion of single crystalline and polycrystalline Li2 ( Li1-xFex) N with x = 0 and x ≈ 0.30 . Magnetic hysteresis emerges at temperatures below T ≈ 50 K with coercivity fields of up to μ0H = 11.6 T at T = 2 K and magnetic anisotropy energies of 310 K (27 meV). The ac susceptibility is strongly frequency-dependent (f = 10 – 10 000 Hz) and reveals an effective energy barrier for spin reversal of Δ E ≈ 1100 K (90 meV). The relaxation times follow Arrhenius behavior for T > 25 K . For T < 10 K , however, the relaxation times of τ ≈ 1010s are only weakly temperature-dependent, indicating the relevance of a quantum tunneling process instead of thermal excitations. The magnetic entropy amounts to more than 25 J mol-1Fe K-1, which significantly exceeds R ln 2 , the value expected for the entropy of a ground-state doublet. Thermal expansion and magnetostriction indicate a weak magnetoelastic coupling in accordance with slow relaxation of the magnetization. The classification of Li2 ( Li1-xFe x) N as ferromagnet is stressed and contrasted with highly anisotropic and slowly relaxing paramagnetic behavior.
- Research Organization:
- Ames Laboratory (AMES), Ames, IA (United States)
- Sponsoring Organization:
- USDOE; German Research Foundation (DFG)
- Grant/Contract Number:
- AC02-07CH11358
- OSTI ID:
- 1425481
- Alternate ID(s):
- OSTI ID: 1422441
- Report Number(s):
- IS-J-9591; PRBMDO; TRN: US1802113
- Journal Information:
- Physical Review B, Vol. 97, Issue 6; ISSN 2469-9950
- Publisher:
- American Physical Society (APS)Copyright Statement
- Country of Publication:
- United States
- Language:
- English
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