RESUMEN
The subtle interplay of randomness and quantum fluctuations at low temperatures gives rise to a plethora of unconventional phenomena in systems ranging from quantum magnets and correlated electron materials to ultracold atomic gases. Particularly strong disorder effects have been predicted to occur at zero-temperature quantum phase transitions. Here, we demonstrate that the composition-driven ferromagnetic-to-paramagnetic quantum phase transition in Sr(1-x)Ca(x)RuO3 is completely destroyed by the disorder introduced via the different ionic radii of the randomly distributed Sr and Ca ions. Using a magneto-optical technique, we map the magnetic phase diagram in the composition-temperature space. We find that the ferromagnetic phase is significantly extended by the disorder and develops a pronounced tail over a broad range of the composition x. These findings are explained by a microscopic model of smeared quantum phase transitions in itinerant magnets. Moreover, our theoretical study implies that correlated disorder is even more powerful in promoting ferromagnetism than random disorder.
RESUMEN
OBJECTIVES: The General Medical Council has recommended that medical students should gain more experience in general practice. The study set out to determine patients' reactions to consultations conducted by a medical student alone prior to seeing their GP. DESIGN: A random sample of patients attending general practice surgeries in the Oxford area completed a questionnaire following consultation with a medical student. SETTING: Six general practice teaching surgeries. SUBJECTS: Fifth-year medical students. RESULTS: Of 130 responders 98% experienced no disadvantage in seeing the student; 35% considered that there were advantages in seeing the student; 98% said that they would be prepared to consult with a student again; 85% expressed no concerns about the gender of the student. CONCLUSIONS: The results of this study are very reassuring concerning the acceptability to patients of consulting with medical students and are more favourable than those reported for studies of students being present in consultations by GPs.