14 research outputs found
Magnetization steps in a diluted Heisenberg antiferromagnetic chain: Theory and experiments on TMMC:Cd
A theory for the equilibrium low-temperature magnetization M of a diluted
Heisenberg antiferromagnetic chain is presented. The magnetization curve, M
versus B, is calculated using the exact contributions of finite chains with 1
to 5 spins, and the "rise and ramp approximation" for longer chains. Some
non-equilibrium effects that occur in a rapidly changing B, are also
considered. Specific non-equilibrium models based on earlier treatments of the
phonon bottleneck, and of spin flips associated with cross relaxation and with
level crossings, are discussed. Magnetization data on powders of TMMC diluted
with cadmium [i.e., (CH_3)_4NMn_xCd_(1-x)Cl_3, with 0.16<=x<=0.50 were measured
at 0.55 K in 18 T superconducting magnets. The field B_1 at the first MST from
pairs is used to determine the NN exchange constant, J, which changes from -5.9
K to -6.5 K as x increases from 0.16 to 0.50. The magnetization curves obtained
in the superconducting magnets are compared with simulations based on the
equilibrium theory. Data for the differential susceptibility, dM/dB, were taken
in pulsed magnetic fields (7.4 ms duration) up to 50 T, with the powder samples
in a 1.5 K liquid-helium bath. Non-equilibrium effects, which became more
severe as x decreased, were observed. The non-equilibrium effects are
tentatively interpreted using the "Inadequate Heat Flow Scenario," or to
cross-relaxation, and crossings of energy levels, including those of excited
states.Comment: 16 pages, 14 figure
‘A Floating Population’: The Niagara Corridor and Canadian/American Radicalism in the Nineteenth Century
Discrimination in hiring against immigrants and ethnic minorities: the effect of unionization
There has been a long debate concerning whether unions are exclusive or inclusive with respect to immigrants and ethnic minorities. In the exclusive view of unions, unionization is expected to increase the likelihood of employers asking questions that discriminate against immigrants and ethnic minorities and decrease the likelihood of employers asking Equal Employment Opportunity (EEO) questions related to immigrant or ethnic minority status. The contrary is expected for the inclusive view. Our analysis, using New Zealand data for job applications, provides some support for the inclusive view of unions, as the higher the unionization rate, the more likely EEO information is sought, but no relationship is found between unionization rate and discriminatory questioning. This suggests that unions are probably helpful in promoting diversity but not yet in combating discrimination against immigrants and ethnic minorities in hiring