High Resistivity and Diamagnetism in AlPdMn Icosahedral Phase

Abstract

PACS. 61.40 -Amorphous and polymeric materials. PACS. 72.15C -Electrical and thermal conduction in amorphous and liquid metals and PACS. 75.203 -Metals and alloys. alloys.

Isotropic magnetoresistance of icosahedral Al-Pd-Mn

“…The overall behavior with a comparatively flat maximum at intermediate temperatures of order 50-100 K is in agreement with previous reports on single-as well as polygrained i-Al-Pd-Mn. [2][3][4][5][6]8 With some scatter for the samples at intermediate positions, it can be seen from Fig. 2 that there is a clear trend for a stronger temperature dependence and an increasing maximum in (T)/(300 K) when moving in the growth direction from top to bottom of the sample, together with a weak tendency for a decreasing temperature of the maximum resistivity in the same sequence.…”

“…Although work on single grained i-Al-Pd-Mn show similar maxima, [2][3][4][5][6] results for polygrained samples indicate that such a maximum may depend on annealing conditions and on Mn concentration, 3,8 with a tendency for this maximum to develop with decreasing Mn concentration below about 10 at. % and to be suppressed again below about 8 at.…”

“…7 However, also below this limit the low-temperature paramagnetism is strongly dependent on Mn concentration. 8 Furthermore, minute precipitates of Mn-rich phases, extrinsic to the icosahedral phase, could have a strong influence on the transport properties. Our previous investigations have been performed on samples at the present state of the art of single grain quasicrystal growing, and in particular, have been found to be homogenous with respect to manganese concentration to within 0.2 wt % in sample pieces of 1-cm length from different parts of the ingot.…”

The effect of thermal treatment on the magnetic state and cluster-related disorder of icosahedral Al–Pd–Mn quasicrystals

“…A striking example are magnetic properties of icosahedral i-Al-Pd-Mn QCs, where a study [2] of a large number of samples with the Mn concentration in the range between 7.5 and 8.6 atomic %, showing different morphologies (single-crystalline and polygrain) and subjected to different thermal treatments (annealing temperature and time, followed by either RC or SC cooling mode to RT), has reported that the magnetic Mn fraction in the samples varies over two orders of magnitude (from 3.8 Â 10 -5 to 2 Â 10 -3 ). Thermal annealing resulted in a reduction of the magnetization by as much as a factor of 8 [3,4]. It was also demonstrated [5,6] that the choice of the cooling rate after the annealing period strongly affects the magnetization of the i-AlPd-Mn QCs in a reversible way, with slowly cooled samples being systematically less magnetic than the rapidly cooled ones.…”

The question of intrinsic origin of the metal-insulator transition in i-AlPdRe quasicrystal

“…In i-AlPdMn, single-grains with conductivities as low as that found in best quenched and annealed i-AlPdMn ribbons [25] was a many year effort. Not only chemical composition tuning but also single-grains post-growth annealing are crucial [26].…”