TY - JOUR
T1 - Magnetic properties, Mössbauer and specific-heat studies of R1.5Ce0.5Sr2FeCu2O9 (R = Y, Eu, Gd and Dy) compounds
AU - Felner, I.
AU - Schmitt, D.
AU - Barbara, B.
PY - 1997/1
Y1 - 1997/1
N2 - We have investigated R1.5Ce0.5Sr2FeCu2O9 materials by complementary experimental techniques. All materials studied are not superconducting and the magnetic-susceptibility data reveal a magnetic anomaly for R = Y and Eu at TN = 31 and 47 K, respectively. The anomaly is sensitive to oxygen concentration and shifts toward 260 K when oxygen is depleted. Mossbauer spectroscopic studies reveal two inequivalent iron sites, and that the Fe ions reside (60%) predominantly in the Cu(1) site. In both sites, the Fe does not order magnetically, and the low TN obtained in this system, as compared to other isostructural materials, is due to frustration of the Cu moments by the presence of Fe in both sites. While the anomalies are clearly identified by magnetic measurements, no specific heat anomaly was observed at TN. A strong two-dimensional quantum spin fluctuation is considered to be the cause of the unusual behavior at TN of Cu.
AB - We have investigated R1.5Ce0.5Sr2FeCu2O9 materials by complementary experimental techniques. All materials studied are not superconducting and the magnetic-susceptibility data reveal a magnetic anomaly for R = Y and Eu at TN = 31 and 47 K, respectively. The anomaly is sensitive to oxygen concentration and shifts toward 260 K when oxygen is depleted. Mossbauer spectroscopic studies reveal two inequivalent iron sites, and that the Fe ions reside (60%) predominantly in the Cu(1) site. In both sites, the Fe does not order magnetically, and the low TN obtained in this system, as compared to other isostructural materials, is due to frustration of the Cu moments by the presence of Fe in both sites. While the anomalies are clearly identified by magnetic measurements, no specific heat anomaly was observed at TN. A strong two-dimensional quantum spin fluctuation is considered to be the cause of the unusual behavior at TN of Cu.
KW - Magnetic properties
KW - RCeSrFeCuO
KW - Specific heat
UR - http://www.scopus.com/inward/record.url?scp=0030737036&partnerID=8YFLogxK
U2 - 10.1016/S0921-4526(96)00513-3
DO - 10.1016/S0921-4526(96)00513-3
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AN - SCOPUS:0030737036
SN - 0921-4526
VL - 229
SP - 153
EP - 166
JO - Physica B: Condensed Matter
JF - Physica B: Condensed Matter
IS - 2
ER -