SPECIFIC HEAT ANOMALY FOR H ≥ 28.5 T IN CeIrIn5
Recently Takeuchi reported a weak, 'metamagnetic-like' increase in the magnetization around 42 T in single crystals of CeIrIn 5 for field in the c-direction. We report specific heat measurements on single crystal CeIrIn 5, H parallel c-axis, measured in the dc hybrid magnet at NHMFL in Tallahassee between 1.4 and 10 K. A clear anomaly in C/T in 35 T is observed to peak at 1.8 K, with an entropy of 6% of RIn2. This anomaly grows in size and shifts upwards in temperature (both monotonically) with increasing H until at 45 T T peak =4.1 K , with the entropy associated with the transition equal to 14% of RIn2. C/T data at 32 T show3 only the high temperature side of the peak occurring above 1.4 K, while C/T data at 28.5 T show no anomaly down to 1.4 K. This is consistent with our Tpeak vs H data, which imply T peak → 0 at 26 T.