Field Dependence of the Magnetic Quantum Phase Transition in {{MnSi}}

The dependence on pressure (P) and field (H) of the magnetic phase diagram of MnSi has been investigated by means of measurements of the AC susceptibility ##IMG## [http://ej.iop.org/images/0953-8984/9/31/019/img1.gif] up to 16 kbar and 7 T at temperatures down to 30 mK. For ambient pressure, we report on a peak in ##IMG## [http://ej.iop.org/images/0953-8984/9/31/019/img2.gif] above ##IMG## [http://ej.iop.org/images/0953-8984/9/31/019/img3.gif] at a characteristic temperature ##IMG## [http://ej.iop.org/images/0953-8984/9/31/019/img4.gif] that rises quickly with field. The pressure dependence of ##IMG## [http://ej.iop.org/images/0953-8984/9/31/019/img4.gif] is found to be strongly analogous to that of the zero-field transition to long-range order at ##IMG## [http://ej.iop.org/images/0953-8984/9/31/019/img3.gif] . Features of ##IMG## [http://ej.iop.org/images/0953-8984/9/31/019/img2.gif] in the field versus temperature (T) phase diagram may be viewed as ‘fingerprint' evidence of a field-induced crossover at ##IMG## [http://ej.iop.org/images/0953-8984/9/31/019/img4.gif] of the itinerant magnetism from a non-polarized regime at high T and low H to a polarized regime at low T and high H. The long-wavelength spin spiral, present at low H, appears to be supported only in the polarized regime, so in the immediate vicinity of the critical pressure ##IMG## [http://ej.iop.org/images/0953-8984/9/31/019/img9.gif] for which ##IMG## [http://ej.iop.org/images/0953-8984/9/31/019/img10.gif] , a small pocket exists as a re-entrant state.     «

The dependence on pressure (P) and field (H) of the magnetic phase diagram of MnSi has been investigated by means of measurements of the AC susceptibility ##IMG## [http://ej.iop.org/images/0953-8984/9/31/019/img1.gif] up to 16 kbar and 7 T at temperatures down to 30 mK. For ambient pressure, we report on a peak in ##IMG## [http://ej.iop.org/images/0953-8984/9/31/019/img2.gif] above ##IMG## [http://ej.iop.org/images/0953-8984/9/31/019/img3.gif] at a characteristic temperature ##IMG## [http://ej.i...     »