Abstract:
|
Measurements of Mössbauer absorption spectra of
57
Fe
:
La
2
Ni
O
4
at 297, 77, and 4.2 K provide evidence, at the lowest temperatures, of magnetic order in a sample containing
57
Fe
3
+
-ion impurities and some
La
2
+
n
Ni
1
+
n
O
4
+
3
n
intergrowth. Mössbauer emission spectra of
57
Co
:
La
2
Ni
O
4
at 77 and 4.2 K show magnetic order coexisting with paramagnetism in a sample containing a small concentration of
57
Co
-ion impurities and some
La
2
+
n
Ni
1
+
n
O
4
+
3
n
intergrowth. These results are interpreted as evidence for competition between magnetic ordering and charge-density-wave formation among electrons of a narrow
σ
∗
x
2
−
y
2
band; intergrowths, impurities, and nonstoichiometry favor magnetic ordering. |