Abstract
The proton resonance line in (NH4)2IrCl6 powder is narrow due to rapid NH4+ tunnelling, even below the antiferromagnetic temperature TN=2.15K, and proton relaxation T1 gives information about Ir4+ psin dynamics. Spin correlation above TN results in T1 varies as )(T-TN)/TN)0.27+or-0.07 which may be explained with the dynamic scaling hypothesis of critical exponents. From 2.15K to 2.00K T1 increases by a factor of the order of 200, and below 2.00K the authors find the direct relaxation process T1 varies as T-1 for the tunnelling NH4+ ions (NH4)2ReCl6 behaves similarly, with TN approximately=10K.

This publication has 19 references indexed in Scilit: