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In: Energymaterials

Even if quantum physics is well established since roughly ninety years, there are still some quantum effects in matter which have been theoretically predicted but up to now not yet seen experimentally. It was the physicist Hans Bethe, who first described theoretically in 1931 what happens in a one dimensional quantum spin system: under certain conditions, magnetic  excitations may interact and give rise to a collective excitation, known as “Bethe strings”.  But in real matter, strictly one dimensional systems are rare, so Bethe strings have not been a common phenomenon. Now those Bethe strings have been discovered for the first time experimentally by the AugsburgRead More →

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In: Neutrons

An international team has examined pristine and slightly doped bismuth ferrite using experimental data obtained at HZB. The research shows the sequence of serial and trigger-type phase transitions, the temperature-dependent behavior of the order parameters, and the corresponding susceptibilities to external stimuli.  The material: Multiferroics are materials that exhibit multiple types of ferroic ordering, such as ferromagnetism and ferroelectricity, simultaneously. BiFeO3 (BFO) is the one of the rare multiferroics with a strong ferroelectric polarization, antiferromagnetism at room temperature as well as conduction and magnetotransport at domain walls. This makes it a candidate for a range of applications. The question: What are the underlying physical mechanismsRead More →