skip to main content

DOE PAGESDOE PAGES

This content will become publicly available on February 23, 2019

Title: Ferromagnetism versus slow paramagnetic relaxation in Fe-doped Li 3 N

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 Li 2 ( Li 1-xFe x) N with x = 0 and x ≈ 0.30 . Magnetic hysteresis emerges at temperatures below T ≈ 50 K with coercivity fields of up to μ 0H = 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 ≈ 10 10s 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 -1 Fe 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 classificationmore » of Li 2 ( Li 1-xFe x) N as ferromagnet is stressed and contrasted with highly anisotropic and slowly relaxing paramagnetic behavior.« less
Authors:
 [1] ;  [2] ;  [3] ;  [4] ;  [4] ;  [5] ;  [1] ;  [3] ;  [6]
  1. Univ. of Augsburg (Germany). EP VI, Center for Electronic Correlations and Magnetism, Inst. of Physics
  2. 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)
  3. Univ. of Augsburg (Germany). Chair of Solid State Chemistry, Inst. of Physics
  4. Technische Universitat Dresden, Dresden (Germany). Inst. for Solid State and Materials Physics
  5. Univ. of Augsburg (Germany). EP VI, Center for Electronic Correlations and Magnetism, Inst. of Physics; IIT Tirupati, Tirupati (India). Dept. of Physics
  6. Ames Lab. and Iowa State Univ., Ames, IA (United States); Iowa State Univ., Ames, IA (United States). Dept. of Physics and Astronomy
Publication Date:
Report Number(s):
IS-J-9591
Journal ID: ISSN 2469-9950; PRBMDO
Grant/Contract Number:
AC02-07CH11358
Type:
Accepted Manuscript
Journal Name:
Physical Review B
Additional Journal Information:
Journal Volume: 97; Journal Issue: 6; Journal ID: ISSN 2469-9950
Publisher:
American Physical Society (APS)
Research Org:
Ames Laboratory (AMES), Ames, IA (United States)
Sponsoring Org:
USDOE; German Research Foundation (DFG)
Country of Publication:
United States
Language:
English
Subject:
75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND SUPERFLUIDITY
OSTI Identifier:
1425481
Alternate Identifier(s):
OSTI ID: 1422441