Independent magnetic ordering of the
Er and Fe sublattices in ErFe6Sn6
J.M. Cadogan and D.H. Ryan
Department of Physics and Astronomy, University of Manitoba
Winnipeg, MB, R3T 2N2, Canada
E-mail: cadogan@physics.umanitoba.ca
Department of Physics, McGill University
Montreal, QC, H3A 2T8, Canada
E-mail: dhryan@physics.mcgill.ca
ErFe6Sn6
• ErFe6Sn6 is orthorhombic (Cmcm)
• There are two Er sites, five Fe
sites and ten Sn sites
• RFe6Ge6 and RFe6Sn6
intermetallics show the somewhat
unusual phenomenon of
independent magnetic ordering of
the R and Fe sublattices [1].
• Fe orders antiferromagnetically at
555 K. The Er ordering takes
place at 5 K, without affecting the
Fe order [2].
•
The Er is located between
ferromagnetic planes of Fe,
whose antiferromagnetic
interplanar coupling leads to
a zero net exchange field at
the Er site.
Mössbauer spectroscopy of 166Er
The 80.6 keV Mössbauer gamma-ray arises from the transition between the I=2
excited nuclear state and the I =0 ground state of the 166Er nucleus.
166Ho
b−
I=2
80.6 keV, 1.9 ns
I=0
0 keV
27 hr
166Er
A more detailed description of the 166Er experiment can be found
in our article on Er3Ge4
Magnetic ordering in ErFe6Sn6
Fe magnetic ordering at 555 K
detected by Differential Scanning
Calorimetry
Er magnetic ordering at 5 K
detected by ac-susceptibility
Magnetization of the Er sublattice
• Magnetometry at 2 K shows that the Er sublattice magnetic order
comprises both FM and AF components
• M remains unsaturated up to 9 T.
Neutron powder diffraction
Hahn-Meitner Institute, Berlin
The magnetic scattering from the Er sublattice
is quite weak.
A Mössbauer triptych
57Fe
119Sn
166Er
Note the
different
velocity scales!
• The 57Fe Mössbauer spectrum shows the (AF) order of the Fe
sublattice, with an Fe moment of 1.7 mB at RT.
• The 119Sn Mössbauer spectrum shows two components, one of
which is magnetically split. Sn is non-magnetic so the Sn nuclei
only see transferred hyperfine fields from their (magnetic)
surroundings. The relative areas of the two components in the
119Sn Mössbauer spectrum are fully consistent with the magnetic
structures of the Er sublattices (sites) determined by neutron
diffraction. As such, the 119Sn Mössbauer work provides an
excellent verification of the neutron diffraction results.
• The 166Er Mössbauer spectrum obtained at 2 K shows that the Er3+
magnetic moment in ErFe6Sn6 is 8.5(1) mB, close to its free-ion
value (9 mB)
Er sublattice magnetic order in ErFe6Sn6
Er 4c1 site.
Er 4c2 site.
Open circles represent the z =1/4 plane,
Hatched circles represent the z =3/4
plane.
• This study demonstrates the powerful complementarity of Mössbauer
Spectroscopy (a local magnetic probe) and Neutron Diffraction (an
extended-scale measurement)
• Neutron diffraction gives the FM and AF components of the magnetic
order
• 166Er Mössbauer Spectroscopy gives the total local Er3+ moment.
• 57Fe Mössbauer Spectroscopy gives the total local Fe moment.
• 119Sn Mössbauer Spectroscopy provides verification of the magnetic
structure.
References
[1]
[2]
J.M. Cadogan and D.H. Ryan, J. Alloys. Comp. 326, 166-73 (2001)
J.M. Cadogan et al. J. Phys.: Condensed Matter 15, 1757-71 (2003)