Dr. John Loram 1938-2017
John Loram studied at Imperial College, London University, receiving his B.Sc. with First Class Honours and being awarded the Governors' prize in 1958. He stayed on to complete his Ph. D research there in 1964. He then became a lecturer and researcher in physics at the University of Sussex. Much of his early research involved magnetic and transport measurements of metallic alloys in connection with the Kondo effect, exchange enhancement and spin glass behaviour. But a considerable advance was made when he designed and developed a unique high resolution (1:104) differential calorimeter operating over the temperature range 1.5 to 300 K. This made possible, for the first time, the reliable separation of the large background phonon specific heat from small changes in electronic, magnetic and phonon terms across an alloy series.
After initial investigations at Sussex University of the new high temperature cuprate superconductors, in 1989 he joined the measurement laboratory of the newly-founded Interdisciplinary Research Centre in Superconductivity at the University of Cambridge. Here he worked as a physicist collaborating with chemists, materials scientists, engineers and theorists in the development of new or improved superconducting compounds. Although he was closely involved with the measurement and interpretation of many properties, his main experimental contribution was in differential calorimetry. He measured hundreds of samples of several families of cuprate superconductors over a wide range of temperature and carrier concentration. These data continue to provide vital information about the electronic specific heat that cannot be obtained by other means. For example he showed that the pseudogap, whose origin is still not fully understood, is (a) a gap in both the charge and spin excitation spectra (b) sets in abruptly below a certain hole concentration and (c) strongly weakens the strength of the superconductivity without initially lowering the superconducting transition temperature.
In 2004 he joined the QM research group and moved his calorimeter, by now improved and semi-automated, to the Mott building. Although partially retired, he continued to make important contributions to our research programme until only a couple of days before his untimely passing.
Sadly we have lost one of the most insightful and effective condensed matter physicists of his generation.