A sensitive capacitance thermometer at low temperature for use in magnetic fields up to 20 T

Abstract

We have established the magnetic-field independence up to 20 T of a capacitance thermometer based on the incommensurate crystal ͑Pb 0.45 Sn 0.55 ͒ 2 P 2 Se 6 in the temperature range from 25 mK to 0.5 K. The sensitivity of the thermometer, d ln C/d ln T, is 5ϫ10 Ϫ3 at low temperatures and is about an order of magnitude larger than for any other previously reported capacitance thermometer. The most sensitive temperature range of the thermometer can be tuned by varying the measuring ac frequency and voltage. The reproducibility of the thermometer upon cycling below 1 K is better than 1 mK.

Review of temperature measurement

“…88 The permittivity-temperature characteristics have been studied for a variety of materials. [89][90][91][92][93][94][95][96][97] Commercial devices are available from Lake Shore Cryotonics Inc.…”

Phase diagram of ferroelectrics with tricritical and Lifshitz points at coupling between polar and antipolar fluctuations

“…Such peculiarity can be seen on the excess heat capacity ∆C p and anomalous temperature dependencies of dielectric susceptibility ε ′ in (Pb y Sn 1−y ) 2 P 2 Se 6 crystals, according to recent investigations. 15,16,57,58 For small lead concentrations, there are clear anomalies of ∆C p (T ) and ε ′ (T ) at paraelectric-incommensurate (T i ) and incommensurateferroelectric (T c ) phase transitions (see Fig. 4, 5).…”

“…5. Comparison of the anomalies for low frequency dielectric susceptibility (according to data 15,16,58 ) and excess heat capacity (according to data 57 ) in the region of the phase transitions for (PbySn1−y)2P2Se6 crystals.…”

“…[4][5][6][7] The chalcogenide ferroelectrics of Sn 2 P 2 S 6 family also present a rich set of scenarios for critical behavior realization 8,9 and comparison with the theoretical investigations. 10,11 Ferroelectrics of the Sn 2 P 2 S 6 family are promising candidates for application in red and near-infrared spectral diapason photorefraction 12 and photovoltaics, 13 for energy storage 14 and low temperature thermometry, 15,16 as well as development of multilevel-cell-type memory technology. 17 Possibilities of ultrafast spontaneous polarization switching 18 and peculiarities in the ferroelectric ordering and domain structure morphology at nanoscale 19,20 are also important for new technologies based on ferroics with linear and nonlinear coupling be-tween unstable lattice polar modes and antipolar or antiferrodistorsive degrees of freedom.…”

NaCeP2Se6, Cu0.4Ce1.2P2Se6, Ce4(P2Se6)3, and the Incommensurately Modulated AgCeP2Se6: New Selenophosphates Featuring the Ethane-Like [P2Se6]4- Anion

“…Several members of this structure type, such as Sn 2 P 2 S 6 and Sn 2 P 2 Se 6 , show ferroelectric−paraelectric phase transitions and have recently attracted attention as promising materials for use in memory devices . (Pb 0.45 Sn 0.55 ) 2 P 2 Se 6 is useful as a sensitive and tunable thermometer at low temperatures, as it is unaffected by large magnetic fields (up to 20 T) . Here we report the synthesis, structure, and optical and Raman spectroscopic properties of NaCeP 2 Se 6 , Cu 0.4 Ce 1.2 P 2 Se 6 , Ce 1.33 P 2 Se 6 , and AgCeP 2 Se 6 .…”