I am working in Barium ruthenate triple perovskites. I have been observing proper downward peaks at about 30 K, with the minima shifting to higher temperature for higher frequencies. The magnitude of the dips is also higher for higher frequencies. An exactly opposite trend is seen in the imaginary part of ac susceptibility data at the same temperature. There is no transition visible at 30 K in the DC magnetization or heat capacity data. The measurement was carried out in the Quantum Design SVSM MPMS3 multiple times and from multiple instruments at a magnetic field of 3 oe. I have observed this in two different Barium ruthenate triple perovskite compounds of mine. I had also carried out the ac susceptiility measurement in ACMS option of QD PPMS with 13 Oe magnetic field and this anomaly at 30 K is absent. Figures are given for reference.
The magnetic transitions in the sample observed in the dc magnetic susceptibility is getting masked due to this feature. As the measurement with higher applied field in a lower sensitivity instrument doesn't show this feature in contrast to measurement from two different MPMS3 SVSM, I am confused about the authenticity of the data. No other samples are showing similar features in the before said MPMS3. Also, two different triple perovskite compounds of mine showed this feature. Kindly help to understand and analyze this feature.
Rana Hamza Shakil
Actually my concern is the dip (downward peaks) in the ac susceptibility data. I have never seen downward peaks in ac suscceptibility. Even when there are reports of negative peaks in the imaginary part of ac susceptibility (which itself is little tricky to believe) https://www.researchgate.net/post/What_could_be_the_reason_for_anomalous_frequency_dispersion_in_Single_crystal_BiFeO3 there is no report of negative real part, unless in some superconductors.
We have observed that the AC phase angle vs Temperature also peaks around 30 K. Can this be a artifact in that case? Can we subtract this effect and get the original data? If so, how? Figure given for refrence.
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