Detailed investigation of the magnetic phase diagram of ${CeRu}_{2} {Ge}_{2}$ up to 11 GPa

The electrical resistivity

ρ (T)

and transverse magnetoresistivity of magnetically ordered

{CeRu}_{2} {Ge}_{2}

{(T}_{N} = 8.55 K

and

T_{C} = 7.40 K)

was measured as a function of pressure up to

P = 11 GPa

and down to

T = 30

mK. Pressure first increases

T_{N}

and suppresses

T_{C} .

Then a second transition, corresponding probably to a modification of the AFM state, appears at

T_{L} < T_{N}

in the pressure range

3.5 < P < 7.2 GPa .

The long-range magnetic order disappears at a critical pressure

P_{c} = 8.7 GPa

T_{N} \propto {(P}_{c} - {P)}^{m},

with

m = 0.71 (8) .

The

ρ (T)

curves at low temperature and low pressure

(P < 7.8 GPa)

are well described by a power law

ρ (T) \propto T^{n},

with exponents

n > 2.

Well above

P_{c},

a Fermi liquid behavior

(n = 2)

is observed and the A coefficient of the quadratic T dependence decreases with pressure. In the pressure interval

P_{c} \pm 0.8 GPa,

exponents close to

n = 1.5

indicate a deviation from a Fermi liquid description. The magnetoresistivity curves show different anomalies at characteristic magnetic fields

B_{a}, B_{c},

and

B_{M} .

The latter occurs close to

P_{c}

and is reminiscent of the metamagneticlike field in

{CeRu}_{2} {Si}_{2} .

A quantitative comparison between the

(T, P)

data of

{CeRu}_{2} {Ge}_{2}

and the

(T, x)

data of

{CeRu}_{2} ({Si}_{1 - x} {Ge}_{x})_{2}

on the basis of the unit-cell volume as the crucial parameter shows that the same

(T, V)

diagram is obtained.

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Detailed investigation of the magnetic phase diagram ofCeRu2Ge2up to 11 GPa